Available PhD Positions

Project Title & Abstract

Research Area


Order by:  
Filter by:

Supervisor


Order by:  
Filter by:

2D organic nanomaterials for future electronics, optoelectronics and spintronics

Modern electronics relies on the control of electric charge in functional materials and devices. Current mass production methods for device miniaturisation are not only reaching their inherent limit, but are also facing fundamental challenges arising from quantum phenomena at the nanoscale. The design of next-generation electronic devices requires the development of radically new approaches to nanotechnology, including novel materials to supplement or substitute silicon as the active material. The aim of this project is to design electronically functional solid-state devices based on two-dimensional (2D) organic nanomaterials. We will synthesise the latter via supramolecular self-assembly on surfaces, in order to achieve atomic-scale precision and tailored electronic, optoelectronic and magnetic properties. These organic nanomaterials offer extraordinary tunability and extensibility, spanning from the micro- down to the nanoscale. We will design devices where these active 2D organic nanomaterials will be connected to macroscopic electrodes, allowing to access their electronic transport properties, bridging the gap between atomic-scale structure and mesoscopic electronic functionality. The PhD candidate will gain expertise in experimental surface science, nanoscience, supramolecular chemistry, low-temperature physics, scanning tunnelling microscopy and spectroscopy, atomic force microscopy, electron transport, nanofabrication and ultrahigh vacuum. The candidate will perform experiments, analyse and interpret experimental data, compare these experimental data with theoretical models (developed by theoretical collaborators (e.g. with expertise in density functional theory) or the PhD candidate her/himself, time permitting). S/he will conduct his own research project independently. S/he will work within a research team and acquire relevant expertise in the aforementioned fields of research. The PhD candidate will be supervised by Schiffrin and his team.

Applicants should hold an Honours or Master’s degree, and have a strong background in experimental physics.

If you have any questions, please contact Dr Agustin Schiffrin at Agustin.Schiffrin@monash.edu.

Interested applicants must meet Monash Universities PhD entry requirements. See following link: http://monash.edu/science/about/schools/physics/postgrad/apply-postgrad.html.


Condensed Matter Physics
Dr Agustin Schiffrin

3D Coherent X-ray Imaging for Breast Cancer Diagnosis:

Breast cancer is a major cause of cancer-related deaths around the world, with around eight Australians dying every day from this disease. Mammography (X-ray imaging of the breast) is the primary technique used in the diagnosis of breast cancer. However, it only produces low-contrast 2D images that are only accurate in detecting cancer between 67% and 80% of the time, with accuracy highly dependent on tissue density and homogeneity [1].  Furthermore, mammography delivers non-negligible radiation dose that can potentially cause cancer and it requires the breast to be compressed, which creates considerable discomfort for patients.

Using synchrotron radiation, we have recently shown that propagation-based phase-contrast tomography (PB-CT) can remove the need for breast  compression, whilst providing high-resolution, high-contrast 3D images of the tissue. Compared to conventional CT, PB-CT can deliver more than 20-fold improvement in the signal-to-noise ratio (SNR) at the same X-ray dose, or up to a 400-fold reduction in the X-ray dose without a loss in the imaging quality [2].

Using a newly constructed micro-focus phase contrast X-ray imaging system at Monash University, we aim to determine if this technology can be developed into a clinically compatible system that can greatly reduce the false positive and false negative rates of breast cancer diagnosis.

References

[1] ] von Euler-Chelpin, M., Lillholm, M., Vejborg, I. et al. Sensitivity of screening mammography by density and texture: a cohort study from a population-based screening program in Denmark. Breast Cancer Res 21, 111 (2019).

[2] Gureyev, T.E., S. C. Mayo, Y. I. Nesterets, S. Mohammadi, D. Lockie, R. H. Menk, F. Arfelli, K. M. Pavlov, M. J. Kitchen, F. Zanconati, C. Dullin, and G. Tromba, Investigation of the imaging quality of synchrotron-based phase-contrast mammographic tomography, Journal of Physics D: Applied Physics 47, 365401 (2014).

Imaging Physics Associate Professor Marcus Kitchen,
Dr Tim Gureyev (University of Melbourne)

Artificial-intelligence-controlled atom-by-atom synthesis of 2D quantum materials

Scanning probe microscopy (SPM) has revolutionized the fields of surface physics, nanoscience and materials engineering. Not only does it enable mapping of nanoscale surface properties, but it also allows for atomic and molecular manipulation on surfaces with atomic precision. That is, it opens the door for synthesising advanced materials from the bottom-up, atom by atom, and molecule by molecule. However, this usually requires constant supervision by a human expert.

The project here aims to develop a fully automated SPM system based on artificial intelligence (AI) for bottom-up atomic-scale fabrication of advanced 2D quantum materials. The AI framework will combine algorithmic approaches with machine learning (e.g., supervised, deep reinforcement), allowing for high-throughput engineering of atomically precise functional materials with tailored quantum mechanical properties, and paving the way for novel electronic, optoelectronic, spintronic and catalytic functionalities.

The PhD candidate will gain expertise in advanced functional nanomaterials, atomic-scale characterisation and fabrication by low-temperature scanning probe microscopy (STM), automation and machine-learning programming applied to fundamental experimental research.
This project is within a collaboration between Monash University and the University of Melbourne. The PhD candidate will be supervised by Dr. A. Schiffrin (School of Physics and Astronomy, Monash University) and Dr. M. Usman (School of Engineering, University of Melbourne).

Applicants should hold an Honours or Master’s degree, and have a strong background in experimental physics.

If you have any questions, please contact Dr Agustin Schiffrin at Agustin.Schiffrin@monash.edu.

Interested applicants must meet Monash Universities PhD entry requirements. See following link: http://monash.edu/science/about/schools/physics/postgrad/apply-postgrad.html.


Condensed Matter Physics
Dr Agustin Schiffrin, Dr Muhammad Usman

Atomic-scale structural, electronic and optoelectronic studies on light-harvesting metal-halide perovskites

Hybrid organic-inorganic perovskites are an emerging class of photovoltaic and optoelectronic materials. For example, solar cells made of metal-halide perovskite material yield efficiencies beyond 20%. However, the underlying physical mechanisms allowing for strong light absorption and efficient electron-hole separation in metal-halide perovskites are not fully understood. In particular, very few studies have been performed on the atomic-scale properties of these materials. This project aims to combine expertise in synthesis, crystal growth, solar cell assembly and morphology control, with scanning-probe based surface analysis, in order to deepen our understanding of the structural, electronic and optoelectronic properties of perovskite materials at the atomic scale. The PhD candidate will study the atomic-scale structural, electronic and optoelectronic properties of such materials by low-temperature scanning tunnelling microscopy (STM) and spectroscopy (STS), non-contact atomic force microscopy (ncAFM), as well as synchrotron-based x-ray studies (x-ray photoelectron spectroscopy (XPS), near-edge x-ray absorption fine structure (NEXAFS)). These experiments will allow to correlate atomic-scale electronic structure and properties with the materials’ light-harvesting and optoelectronic functionality.

Applicants should hold an Honours or Master’s degree, and have a strong background in experimental physics.

If you have any questions, please contact Dr Agustin Schiffrin at Agustin.Schiffrin@monash.edu.

Interested applicants must meet Monash Universities PhD entry requirements. See following link: http://monash.edu/science/about/schools/physics/postgrad/apply-postgrad.html.


Condensed Matter Physics
Dr Agustin Schiffrin

Building the standard model of particle cosmology

The standard model of elementary particles is one of the most successful theories in science describing all observable physical processes in the solar system, some to ten significant digits.  Similarly, the LambdaCDM model of cosmology correctly describes the key aspects of our observable universe with a high precision [1].

Excitingly, these two models have a common origin: the standard model of particle cosmology.  This mode, however, is not fully crystallised yet. Its main pillars, the particle explanation of inflation, the origin of visible and dark matter and the nature of dark energy are subject of intense research [1,2].

The aim of this project is to analyse various theories beyond the standard particle model.  These theories have specific predictions for inflation, the matter content of the universe [3], and its vacuum configuration.  These predictions will be used, in conjunction with many of their other consequences, to calculate statistical measures to quantify their plausibility using the novel CosmoBit framework [1,4].

References

[1] GAMBIT Cosmology Workgroup CosmoBit: A GAMBIT module for computing cosmological observables and likelihoods

[2] GAMBIT Cosmology Workgroup Strengthening the bound on the mass of the lightest neutrino with terrestrial and cosmological experiments

[3] Global analyses of Higgs portal singlet dark matter models using GAMBIT Eur.Phys.J.C 79 (2019) 1, 38

[4] GAMBIT Collaboration GAMBIT: The Global and Modular Beyond-the-Standard-Model Inference Tool Eur.Phys.J.C 77 (2017) 11, 784, Eur.Phys.J.C 78 (2018) 2, 98 (addendum)

Particle Physics Professor Csaba Balazs

Convection in massive stars

The final stages of massive stars already forebode the violent fate that ultimately awaits them when they explode as a supernova. In the last phases of their lives, these stars go through ever shorter episodes of nuclear burning in the stellar core and the surrounding shells, which drives increasingly violent convective overturn. Immediately before the collapse of the core to a neutron star, convective motions can reach velocities of several hundred kilometres per second in the silicon and oxygen shell around the iron core.

How these convective motions affect the structure of the stellar core by compositional mixing, transport of angular momentum, and excitation of waves is not yet fully understood. Neither do we yet fully understand how they affect the subsequent collapse and explosion. Today, three-dimensional (3D) simulations of convective burning have become a powerful tool for learning about the deep interiors of massive stars. Such 3D simulations are still limited to relatively short time-scales, and cannot consistently follow the entire lifetime of the last burning stages (silicon core burning and silicon and oxygen shell burning). In this project, you will develop efficient numerical methods to enable long-time simulations of the final burning stages and use them to investigate mixing and angular momentum transport in the innermost convective zones and/or to create better 3D progenitor models for supernova simulations.

Students interested in high-performance computing will acquire first-hand experience with modern supercomputers during the course of their PhD. This is a computational project suited for students with a background in astronomy, applied mathematics, or nuclear/particle physics. Experience with computational fluid dynamics is advantageous.

For inquiries, please contact Dr Bernhard Mueller (bernhard.mueller@monash.edu).

Astronomy & Astrophysics Dr Bernhard Mueller

Dark-field X-ray Imaging using MIST

Recent advances in X-ray imaging can provide much more information about objects than traditional radiography. Using coherent X-ray optics, these techniques can quantify how an object alters the phase of the X-ray wavefield and extract a dark-field signal, which arises from small-angle scattering from unresolvable objects within the object. These new sources of information have proven highly useful for disease detection and materials characterisation [1].

A new technique, called Multimodal Intrinsic Speckle Tracking (MIST) [2], provides a simple and fast way to recover multimodal information about the sample’s absorption, phase and dark-field (coherent scattering) properties. It works by illuminating a random phase screen with coherent X-rays to create a speckled intensity pattern. This pattern is warped in the presence of an object. Decoding this warping reveals how the sample interacted with the coherent X-ray photons. MIST is based on combining a Fokker-Planck description of paraxial X-ray optics, with an optical-flow formalism for X-ray speckle-tracking. Only two images need to be taken in the presence of the sample in order to recover both the phase and dark-field properties of the sample. Like the optical-flow X-ray method which it generalizes, the method implicitly rather than explicitly tracks speckles. Application to X-ray synchrotron data shows the method to be efficient, rapid and stable [2].

Using a newly constructed phase contrast X-ray imaging system at Monash University, we aim to develop MIST for use with compact, micro-focus X-ray systems for clinical and industrial application for disease diagnosis and materials characterisation.

References

[1] M. J. Kitchen, G. A. Buckley, L. T. Kerr, K. L. Lee, K. Uesugi, N. Yagi, and S. B. Hooper, “Emphysema quantified: mapping regional airway dimensions using 2D phase contrast X-ray imaging,” Biomedical Optics Express 11(8), p4176, 2020.

[2] K. M. Pavlov, D. M. Paganin, H. Li, S. Berujon, H. Rougé-Labriet, E. Brun, “X-ray Multimodal Intrinsic-Speckle-Tracking”, arXiv:1911.06814, 2019.

Imaging Physics Associate Professor Marcus Kitchen,
Dr Konstantin Pavlov (University of Canterbury)

Detecting gravitational waves with Advanced LIGO

The Laser Interferometer Gravitational-wave Observatory (LIGO) seeks to detect gravitational waves: ripples in the fabric of spacetime caused by violent astrophysical events such as the coalescence of two stars. The newly upgraded Advanced LIGO detector is expected to begin taking science data in late 2015. At design sensitivity, Advanced LIGO is expected to detect dozens of gravitational wave events every year. The first detections of gravitational waves will be a watershed moment in astronomy, confirming a prediction of general relativity, probing some of the most extreme objects in the Universe, and potentially testing new physics in regimes that are not accessible through other means. This project is to analyse Advanced LIGO data in order to detect gravitational waves. A number of specific research directions are possible depending on student interests including searches for stochastic backgrounds, searches for persistent point sources, and searches for transients. The project will require engagement in multiple facets of gravitational-wave astronomy: working to understand the behaviour of the detector, analysing Advanced LIGO data, and determining the astrophysical implications of the results. As a bonus, the student working on this project will gain highly marketable expertise with Big Data, statistics, and algorithm development. Applicants should have a strong background in physics/astronomy data analysis including experience with computer programming. Experience with astrophysics/cosmology is advantageous.

Astronomy & Astrophysics Dr Eric Thrane

Development of a neutral helium beam microscope

Both light and electrons are routinely used to probe and image structures and have resulted in huge advances in our understanding of the physical world. Probing samples with neutral helium atoms offer advantages over these established techniques due to the low energy and non-reactive nature of the atoms used to probe a surface, and the high spatial resolution (< 1 micron) achievable. This experimental project will be to develop a prototype neutral helium beam microscope capable resolving structures below 100 nm. The project builds on preliminary work in focusing cold (0.1 K) jets of Helium atoms using highly intense (1e16 W/m^2) laser beams to form a narrow, intense atom probe (100 nm diameter) for sample interrogation. Multiphoton ionization of the atoms scattered off a sample, using intense lasers, is used to detect structures and provide imaging. Applicants should have a strong background in experimental physics and experience with laser and/or electron optics is advantageous.

Imaging Physics Dr Alexis Bishop

Femtosecond atomic-scale dynamics on a surface

The advent of scanning tunnelling microscopy more than 30 years ago has allowed for real-space imaging of single atoms and molecules on a surface. Normally, this technique is able to study the equilibrium properties of a system, and does not allow to access real-time ultrafast dynamics occurring at femtosecond timescales. Indeed, the intrinsic time resolution of scanning tunnelling microscopy is dictated by the speed of conventional electronics, which is at best on the order of hundreds of picoseconds. Many processes on surfaces however, such as charge dynamics or vibrations of molecules, can unfold at much faster timescales, below 1 picosecond.

Recent advances in scanning tunnelling microscopy combined with techniques of nonlinear optics, ultrafast photonics and pump-probe spectroscopy have allowed to access ultrafast dynamics of processes on a surface, with real-time sub-picosecond resolution, and, at the same time, real-space single atom resolution. The approach relies on coupling quasi-single-cycle, ultrashort electromagnetic waveforms (e.g., a terahertz, infrared or optical pulse) to the junction of the scanning tunnelling microscope.

The project here consists of investigating structural, charge and magnetization dynamics in photo-active molecular assemblies on surfaces, with sub-picosecond time resolution, and at the scale of a single atom.

Applicants should hold an Honours or Master’s degree, and have a strong background in experimental physics.

If you have any questions, please contact Dr Agustin Schiffrin at Agustin.Schiffrin@monash.edu.

Interested applicants must meet Monash Universities PhD entry requirements. See following link: http://monash.edu/science/about/schools/physics/postgrad/apply-postgrad.html.


Condensed Matter Physics
Dr Agustin Schiffrin

Few- and many-body physics in ultracold atomic gases

Ultracold atomic gases have emerged as an ideal platform for investigating the physics of strongly correlated materials in a highly controllable environment. The Theory of Quantum Matter group at Monash University works primarily at the interface between condensed matter physics and the physics of ultracold atoms. We are particularly interested in systems where strong few-body correlations impact the many-body behaviour. As such, we investigate a wide range of topics, including few-body systems, impurities in degenerate quantum matter, systems out of equilibrium, and low-dimensional systems.

Applications should have a strong background in theoretical physics. Experience with few- and/or many-body physics of ultracold gases would be advantageous, although it is not necessary. A number of specific research directions are possible, depending on the student’s interests.

An introduction to our research group including recent publications can be found at qm.physics.monash.edu

Theoretical & Computational Physics,
Quantum Gases
Associate Professor Meera Parish,
Dr Jesper Levinsen

Graphene as a platform for new topological phases of electronic matter

Graphene is an atom-thick plane of carbon and the basic constituent of graphite. Electrons in graphene behave as massless relativistic particles and obey an analogue of the Dirac equation in two dimensions; the experimental observation of these properties led to the 2010 Nobel Prize in Physics. A variety of schemes have been proposed to realize new electronic states by introducing a mass and bandgap in graphene. One scheme involves transition metal adatoms on graphene which add strong spin-orbit coupling, resulting in a bandgap and a topological insulating quantum spin Hall phase, or, in the case of magnetic order, a quantum anomalous Hall phase. Such phases could carry dissipationless edge currents at room temperature and could be used in future electronics or quantum computing technologies. This PhD project will characterize the electronic properties of graphene with metal adatoms. In the Fuhrer laboratory at Monash adatom-modified graphene will be created controllably in ultra-high vacuum (UHV), and studied with in situ electronic transport measurements and low-temperature scanning probe microscopy capable of imaging the atomic structure of the modified material. Complementary experiments will be carried out at the Australian Synchrotron to probe the electronic structure of adatom-modified graphene using photoemission spectroscopy.

Condensed Matter Physics Professor Michael Fuhrer

High dimensional data visualisation in high energy physics

Many areas of physics produce very large numbers of results that depend on multiple parameters. The parameters can be theoretical, experimental or from modelling. One example would be Higgs physics, where the LHC experiments are releasing many measurements of its properties. In this case the multiple parameters are the Higgs properties. Typically these measurements are compared with theoretical expectations from the standard model. But they can also be parametrised by an effective Lagrangian to search for deviations from the standard model. In this case the multiple parameters are those in the effective theory.

In this project we will begin to implement modern statistical visualisation tools to large, multidimensional data sets with the aim of gaining intuition into the fits that are normally made.  The data sets to be used in the project can be from particle physics, or with a suitable co-advisor, from any area of physics or astrophysics.

Particle Physics Professor German Valencia

Interacting electrons in atomically thin semiconductors

Single atomically thin planes of layered transition metal dichalcogenides such as MoS2 have recently been discovered to be two-dimensional semiconductors with direct bandgaps. Because of their atomically thin nature, electronic screening in these materials is poor, and electron-electron and electron-impurity interactions are unusually strong. The interaction strength is also tunable through changing the surrounding dielectric environment, impossible in conventional semiconductors. This PhD project will experimentally probe the effect of strong electron-electron and electron-impurity interaction in MoS2. In the Fuhrer laboratory at Monash MoS2 devices will be fabricated using lithographic techniques and transferred into ultra-high vacuum (UHV) where they will be studied with in situ electronic transport measurements and low-temperature scanning probe microscopy capable of imaging their atomic structure. Dopants such as alkali metals will be controllably placed on MoS2 and the screening cloud of individual dopant atoms will be imaged at the atomic scale. The effect of dopants on electronic transport properties will be measured directly. Electron-electron interactions will be controlled through the choice of substrate dielectric constant, and the effect on electronic and optical properties will be studied. Low-temperature scanning probe microscopy will be used to search for signatures of exotic interaction-driven physics such as Wigner crystallization at low carrier densities.

Condensed Matter Physics Professor Michael Fuhrer

Light transformed materials

Topological materials – with their unique electronic properties dictated by the topology of quantum mechanical states – are on the verge of revolutionising the fields of advanced materials, electronics and spintronics. For example, some of these materials can transport charge at very low resistance, potentially leading to future applications in low-power electronic technologies.

The project here consists of probing and manipulating – at ultrafast femto and picosecond timescales – the topological phases of matter using quasi-single-cycle, ultrashort electromagnetic waveforms (e.g., a terahertz, infrared or optical pulse). Systems of interest will consist of 2D and 3D topological insulators (e.g. Na3Bi, Bi2Se3, WTe2, MnBi2Te4), transition metal dichalcogenides (e.g. MoS2, WS2), Dirac semimetals (e.g. graphene), etc. These systems will be prepared via chemical vapour deposition (CVD) and molecular beam epitaxy (MBE).

The PhD candidate will gain expertise in experimental nonlinear optics, pump-probe spectroscopy, ultrafast lasers, condensed matter physics and surface science. The candidate will perform experiments, analyse and interpret experimental data, compare these experimental data with theoretical models (developed by theoretical collaborators (e.g. with expertise in density functional theory) or the PhD candidate her/himself, time permitting). They will conduct their own research project independently and will collaborate with other members of Schiffrin’s research group to manage the ultrafast laser system and acquire relevant expertise in the aforementioned fields of research. They will also have the opportunity to participate in experiments at collaborating international institutions. The PhD candidate will be supervised by Schiffrin and Beane, with help from Schiffrin’s research group members.

Applicants should hold an Honours or Master’s degree, and have a strong background in experimental physics.

If you have any questions, please contact Dr Gary Beane at gary.beane@monash.edu or Agustin Schiffrin at agustin.schiffrin@monash.edu

Interested applicants must meet Monash Universities PhD entry requirements. See following link: http://monash.edu/science/about/schools/physics/postgrad/apply-postgrad.html


Condensed Matter Physics
Dr Gary Beane,
Dr Agustin Schiffrin

Low-dimensional electronic and optoelectronic organic quantum materials

Modern electronics and optoelectronics rely on the nanoscale behaviour of electrons in materials. This quantum mechanical behaviour is dictated by the dimensionality, chemistry and atomic-scale structure of the active materials. Molecular self-assembly - i.e., the spontaneous arrangement of organic and metal-organic molecules into well-defined stable or metastable nanoarchitectures - offers compelling avenues for synthesising materials (including low-dimensional) from the bottom-up, with atomic-scale precision.

This aim of this project is to design and study atomically precise low-dimensional nanomaterials based on custom synthesised organic molecules. We aim to achieve nanoscale structural and chemical properties to generate exotic quantum electronic phenomena with potential for novel technologies in nanoelectronics, optoelectronics (light-harvesting, light-emitting) and catalysis.

This project is within the framework of a collaboration between Dr. C. Ritchie’s (School of Chemistry) and Dr. A. Schiffrin’s (School of Physics and Astronomy) groups. Organic nano-building blocks will be synthesised by Ritchie’s group with tailored properties. The atomic-scale structural and electronic properties of the assembled nanomaterials will be characterised in Schiffrin’s group by low-temperature scanning probe microscopy and synchrotron-based techniques.

The PhD candidate will gain expertise in experimental surface science, nanoscience, supramolecular chemistry, low-temperature physics, scanning tunnelling microscopy and spectroscopy, atomic force microscopy, nanofabrication and ultrahigh vacuum. The candidate will perform experiments, analyse and interpret experimental data, compare these experimental data with theoretical models (developed by theoretical collaborators (e.g. with expertise in density functional theory) or the PhD candidate her/himself, time permitting). S/he will conduct his own research project independently. S/he will work within a research team and acquire relevant expertise in the aforementioned fields of research. The PhD candidate will be co-supervised by Ritchie and Schiffrin, as well as their teams.

Applicants should hold an Honours or Master’s degree, and have a strong background in experimental physics.

If you have any questions, please contact Dr Agustin Schiffrin at Agustin.Schiffrin@monash.edu.

Interested applicants must meet Monash Universities PhD entry requirements. See following link: http://monash.edu/science/about/schools/physics/postgrad/apply-postgrad.html.


Condensed Matter Physics
Dr Agustin Schiffrin, Dr Chris Ritchie

Mapping a glassy “phase diagram”

Understanding the nature and structure of materials far-from-equilibrium is one of the remaining grand challenges in condensed matter physics [1]. Far-from-equilibrium phenomena can be seen in many diverse scientific disciplines and across many lengths scales including glasses, cellular systems, granular flows and earthquakes. Thus, advances in the underlying physics of out-of-equilibrium systems can have far-reaching implications across a large range of fundamental and applied areas. Glasses are a prototypical example of materials that are out-of-equilibrium. Yet, scientists have many unanswered questions about these materials. How can a material retain the disordered structure of a liquid, and yet be solid? Why do some materials form glasses more easily than others? What structure underlies the brittle fracture of glasses?

A key impediment to fresh understanding of the glassy state is an experimental technique to measure disordered structures. Current techniques in crystallography can only determine the structure of periodic objects. A series of new and measureable structural parameters for glasses has recently been proposed [2,3] and demonstrated by Monash University researchers using scanning micro-small-angle x-ray scattering [4] and colloidal glasses. In this experiment, it was shown for the first time, how local structures in the colloidal glass could be varied widely by varying the interaction between particles. Intriguingly, this local order in the glass could be linked to the local order in the underlying, lower density, crystalline phase diagram [4].

This project will involve complete mapping of the local order in glassy “phase diagrams” for one and two-component colloidal glasses with round and elliptical particles and a range of interaction-tuning additives. It will involve experiments at the Australian Synchrotron, the Monash Centre for Electron Microscopy and the Ramaciotti Centre for Cryo-EM and collaboration with A/Prof. Rico Tabor (School of Chemistry, Monash university). The project would suit a student with interests in experimental physical chemistry and soft matter, scattering methods and the development of new data analysis tools.

References

[1] National Academy of Sciences Report Condensed Matter and Materials Physics, 2010.

[2] A. C. Y. Liu, M. J. Neish, G. Stokol, G. A. Buckley, L. A. Smillie, M. D. de Jonge, R. T. Ott, M. J. Kramer, and L. Bourgeois, Phys. Rev. Lett. 110, 205505, (2013)

[3] A. C. Y. Liu, R. F. Tabor, L. Bourgeois, M. D. de Jonge, S. T. Mudie, and T. C. Petersen, Phys. Rev. Lett., 116, 205501 (2016)

[4] A. C. Y. Liu, R. F. Tabor, M. D. de Jonge, S. T. Mudie, and T. C. Petersen, Proc. Nat. Acad. Sci., 114, 10344–10349, (2017)

Imaging Physics,
Condensed Matter Physics
Dr Amelia Liu,
Associate Professor Rico Tabor (School of Chemistry)

Modelling the electronic structure of low-dimensional organic nanostructures on surfaces

Supramolecular and metal-organic self-assembly on surfaces holds promise for the synthesis of functional low-dimensional nanostructures with ultimate atomic-scale precision. This approach consists of depositing atoms and functionalised organic molecules onto clean surfaces, in a controlled environment, to achieve well-defined configurations via programmed inter-adsorbate and adsorbate-surface interactions.

Potential functionality of these nano-assemblies arise from their atomic-scale electronic structure, which is dictated by quantum mechanics. Understanding and predicting such electronic structure is non-trivial, given the typically large size of the unit cell of these many-body systems. Density functional theory (DFT) offers a viable numerical method for determining the energy-dependent electronic density in such systems, allowing to understand and predict their morphology and electronic properties at the atomic scale.

The project here consists of using computational tools (e.g., density functional theory, many-body quantum mechanical models) for determining the atomic-scale morphology and electronic structure of low-dimensional nanomaterials on surfaces. Systems of interest will consist of 1D and 2D metal-organic frameworks on metals, semiconductors and atomically thin materials. In particular, these systems are relevant for the design of solid interfaces with functionality in photovoltaics, photocatalysis, molecular nanoelectronics and molecular magnetism. This project will be co-supervised by Dr. Schiffrin (School of Physics and Astronomy) and Prof. Medhekar (Department of Materials Science and Engineering)

Applicants should hold an Honours or Master’s degree, and have a strong background in experimental physics.

If you have any questions, please contact Dr Agustin Schiffrin at Agustin.Schiffrin@monash.edu.

Interested applicants must meet Monash Universities PhD entry requirements. See following link: http://monash.edu/science/about/schools/physics/postgrad/apply-postgrad.html.


Condensed Matter Physics
Dr Agustin Schiffrin,
Professor Nikhil Mendhekar

On-surface organic nano-electronics

Modern electronics relies on the control of electric charge in nanoscale devices. Current mass production methods for device miniaturisation are not only reaching their inherent limit, but are also facing fundamental challenges arising from quantum phenomena at the nanoscale. The design of next-generation electronic devices requires the development of radically new approaches to nanotechnology, including novel materials to supplement or substitute silicon as the active material.

The aim of this project is to design electronically functional nanodevices based on supramolecular self-assembly on surfaces as novel active electronic materials. This approach employs molecules as building blocks to assemble nanostructures with atomic-scale structural precision and tailored electronic functionality. These systems offer extraordinary tunability and extensibility, spanning from the micro- down to the nanoscale. Engineered nanodevices will consist of low-dimensional organic and metal-organic nanostructures, synthesized from the bottom-up with atomic-scale precision. These active materials will be connected to macroscopic electrodes, allowing to access the macroscopic electronic properties of the organic systems via electron transport measurements. This will bridge the gap between atomic-scale electronic structure and overall electronic functionality of the device.

The PhD candidate will gain expertise in experimental surface science, nanoscience, supramolecular chemistry, low-temperature physics, scanning tunnelling microscopy and spectroscopy, atomic force microscopy, electron transport, nanofabrication and ultrahigh vacuum. The candidate will perform experiments, analyse and interpret experimental data, compare these experimental data with theoretical models (developed by theoretical collaborators (e.g. with expertise in density functional theory) or the PhD candidate her/himself, time permitting). S/he will conduct his own research project independently. S/he will work within a research team and acquire relevant expertise in the aforementioned fields of research. The PhD candidate will be supervised by Schiffrin and Weber, with help of other research group members.

Applicants should hold an Honours or Master’s degree, and have a strong background in experimental physics.

If you have any questions, please contact Dr Agustin Schiffrin at Agustin.Schiffrin@monash.edu and Dr Bent Weber at Bent.Weber@monash.edu.

Interested applicants must meet Monash Universities PhD entry requirements. See following link: http://monash.edu/science/about/schools/physics/postgrad/apply-postgrad.html.


Condensed Matter Physics
Dr Agustin Schiffrin, Dr Bent Weber

Optimal correlations

Concurrent localisation in the position and wavelength of any object is constrained by the Heisenberg Uncertainty Principle. Real world applications that seek to maximise such localisation aspects range from synthetic aperture imaging to watermarking digital media. They often rely on the construction of discrete signals with 'all or nothing' properties: an embedded signal is either exactly locatable to within a single pixel position or they remain completely transparent to a large range of probe signals.

This project examines methods to construct large families of discrete signals that have maximal and/or minimal correlations between family members. A recently discovered class of such signals has been extended from binary to multivalued functions. Ideally, these multivalued signals will retain their 'perfect' properties when constructed using purposefully chosen combinations of values (for example functions that have a uniformly flat or linear histogram of grey values). A related goal is to investigate 'ghosts' in N-dimensions. These are N-dimension signed discrete functions whose projected views in less than N dimensions are exactly zero across the full width of the domain they occupy. A longer term goal is to construct compact N-dimensional functions that have optimal correlations and retain the zero sum property.

Imaging Physics Dr Imants Svalbe

Picosecond resolution calorimeter

For upgrade 2 of the LHCb experiment, the calorimeter will have to undergo a complete redesign. With a factor 20 larger number of proton-proton collisions happening at the same time, there will be a huge challenge in separating the showers created by the individual photons and electrons hitting the calorimeter.

The separation of individual showers is usually achieved through a finer granularity of the calorimeter, but with the cells already smaller than the Moliere radius of the showers, there is no gain from going to a finer structure. Instead it is considered to add very accurate timing information about when the shower develops. This will allow for the separation of particles arriving just a picoseconds apart, corresponding to a few cm at the speed of light.If successful, the result will be that the effective number of simultaneous collisions can be lowered from the 20 happening in the same bunch crossing to just a few that are in the same precision timeframe.

The project will involve working within the LHCb collaboration and in particular in the calorimeter upgrade group. It will be a combination of lab work to test new technologies, work at testbeams at CERN or elsewhere to evaluate prototypes and the simulation of different design options. Part of this will centre around the use of machine learning on FPGAs to form part of the DAQ system.

You will gain extensive experience in both hardware and software skills, and in particular their boundary in firms of firmware on embedded chips. This is very valuable experience in both acedemia and industry.

Particle PhysicsProfessor Ulrik Egede

Photoacoustic imaging of cerebrovascular anatomy and function

Photoacoustic (PA) imaging relies on generating ultrasound pressure waves when tissue absorbs a short pulse of light. Usefully it has been shown that photoacoustics can provide imaging of structures at depths of several centimetres beneath tissue and bone. The lack of ionizing radiation, high resolution (1- 100 microns), and tissue discrimination make this technique attractive for medical diagnostics.This experimental project is to develop an imaging system, using PA tomography, to visualise the vascular anatomy of the cerebrovasculature through the intact rat skull using a recently-developed optically-based acoustic sensor. The apparatus is aimed towards use in stroke research, allowing researchers, for the first time, to see the effects that various protocols have, in near real time, on the vascular system of the rat brain. Using the PA sensor system with multi-wavelength excitation will allow measurements of the oxygen delivery capacity of the brain blood vessel network beneath the intact rat skull. The ultimate aim of this project is to extend the use of PA measurement technique to humans to enable visualisation of the damaged region of brain tissue due to stroke. Applicants should have a strong background in experimental physics and experience with optics is advantageous.

Imaging Physics Dr Alexis Bishop

Precise atomic-scale structure determination in thick nanostructures

Knowing where atoms are and how they are bonded is vital to understand the properties and performance of advanced materials. Among various atomic-scale characterisation methods, transmission electron microscopy has proven highly successful for precise structure determination. Breakthrough advances in fast-readout pixel detectors are enabling structure determination at unprecedented resolution. Despite these new tools, reliable structure determination remains restricted to ultrathin (a few nanometers thick) materials – a small subset of all materials of technological interest – as existing methods fail in thicker nanostructures due to multiple scattering of the probe electrons. Overcoming this limitation is the focus of much research [1-3].

This computational project could take several directions, including:

  • Extending existing thin-object reconstruction strategies by developing iterative algorithms to correct for multiple scattering.
  • Comparing phase retrieval strategies for determining the so-called scattering matrix with as few measurements as possible.
  • Developing methods to characterise instrument aberrations from the data itself.
  • Generalising methods to handle non-periodic structures.

References

[1] D. Ren, M. Chen, L. Waller & C. Ophus, ArXiv eprints (2018), arXiv:1807.03886

[2] H.G. Brown et al., Physical Review Letters 121 (2018) 266102

F. Wang, R.S. Pennington & C.T. Koch, Physical Review Letters 117 (2016) 015501

Imaging Physics,
Condensed Matter Physics,
Theoretical & Computational Physics
Dr Scott Findlay

Quantum Batteries

As mobile devices become more and more indispensable to our way of life, it is crucial to have batteries that are both efficient and fast-charging. While batteries based on current technology have achieved a reasonable speed and efficiency, they still perform well below the fundamental limits set by nature, and they are unlikely to be adequate for the next generations of devices. This project seeks to find those fundamental limits using the tools of quantum information theory.We will consider many-body systems as energy storage devices with the aim of enhancing performance as a battery using quantum entanglement. This project is part of a growing effort in quantum thermodynamics that aims to understand the movement of energy in mesoscopic technologies. The overarching aim of this project is to investigate under which conditions a quantum many-body system can be used as a battery, and to determine the optimal procedures for their charging and discharging. This work will eventually lead to designs for a battery with greater energy storage and higher charging power than can be achieved in current (classical) systems. The PhD student will play a central role in this investigation. After an initial period of training, they will work with Drs. Meera Parish, Kavan Modi, Jesper Levinsen and Felix Pollock to design algorithms to search for optimal battery structure within a series of theoretical models. In the course of this project, the student will acquire familiarity with a range of numerical and analytical techniques, from both condensed matter physics and quantum information theory. Applicants should hold a good first class Honours degree and should have a strong background in undergraduate theoretical physics. In addition, this project would suit an applicant with experience of and an interest in programming.

Theoretical & Computational Physics Dr Kavan Modi, Associate Professor Meera Parish, Dr Jesper Levinsen, Dr Felix Pollock

Rapid x-ray phase and dark field imaging

The honours project will involve measuring and quantifying these 'phase-contrast' and ‘dark-field’ signals captured with these methods, specifically when resolved over time. There are opportunities for computational modelling to elucidate the imaging process, experimental implementation on various x-ray sources and numerical analysis of the resulting images.  Depending on the preferences of the student, the project could also look at incorporating new algorithms [5] into the image analysis code.

X-ray imaging has become an essential tool in the medical field, but conventional absorption methods are still limited in their ability to differentiate between different types of soft tissue. Various methods of phase-contrast x-ray imaging enable visualisation of soft tissue by taking advantage of the changes in the direction of x-ray propagation [1].    In addition, a ‘dark field’ signal can be collected that maps scattering by structures that are too small to resolve directly, like the air sacs in the lungs or cracks in manufactured parts [1].  These image modalities are already being applied in biomedical research [2].    However, many of these methods require multiple images to reconstruct the phase or dark-field images, which is an obstacle when imaging breathing, moving subjects or where the total imaging time should not be too long (e.g. airport security).    Therefore, we are developing methods that either work with only a single exposure [3] or that carefully time image capture to match sample/patient movement [4].

References

[1] Marco Endrizzi, “Phase contrast x-ray imaging”, Nuclear Inst. And Methods in Physics Research A (2017).

[2] PhysicsWorld - “Making the invisible visible”

[3] Kaye Morgan, Timothy Petersen, Martin Donnelley, Nigel Farrow, David Parsons and David Paganin, “Capturing and visualizing transient x-ray wavefront topological features by single-grid phase imaging”, Opt. Express 24 (2016).

[4] R. Gradl et al. – Dynamic in vivo chest x-ray dark-field imaging in mice. IEEE transactions on medical imaging, 38(2), pp.649-656 -

[5] K. S. Morgan and D. M. Paganin, 2019. - Applying the Fokker–Planck equation to grating-based x-ray phase and dark-field imaging. Scientific reports, 9(1), pp.1-14. -

Imaging Physics Dr Kaye Morgan

Revealing fundamental physics with gravitational waves

Originating from the time when the Universe was opaque for light, gravitational waves carry information about fundamental physics from the early Universe well above 1 eV energies. Combined with information from the Large Hadron Collider, this enables us to begin to piece together the thermal history of the early Universe at those energies. Gravitational waves are crucial in this since they carry imprints of thermodynamic phase transitions that played an important role in the early Universe.

The mechanism of spontaneous electroweak symmetry breaking, by which all known elementary particles acquire mass, was accompanied by a thermal phase transition in the early Universe. Fundamental fields acquiring a vacuum expectation value, the breakdown of a unified force into the known four forces, and condensing hidden sectors may have caused a succession of phase transitions. Gravitational waves can tell us whether any of these phase transitions were a first order transition.

The aim of this project is to calculate gravitational wave amplitudes and frequencies in well motivated new physics theories that lead to a first order phase transition in the early Universe. We constrain the parameter space of these theories using various particle experiments and astrophysical observation and check whether their gravitational wave signals are in reach of future gravitational wave detectors such as eLISA, DECIGO, BBO, or aLIGO. This project requires a solid background in particle physics, cosmology and excellent analytical and/or numerical skills.

Particle Physics Professor Csaba Balazs

Role of structure in glass formation and mechanical properties

In condensed matter physics, the structure of a material is integral to its nature. Glasses are not an easy fit in this model. At a fundamental level, it is not known how their structure reflects their formation or the properties they subsequently display. For crystals, it is straight-forward: at the liquid-to-crystal phase transition, symmetry is broken and translational symmetry arises. The new phase is rigid and this property is determined by the broken symmetry of the structure. The force exerted on any particle in the array is cancelled by neighbours. When the cohesive lattice force is overcome, the crystal deforms via the creation and propagation of lattice defects.

Glasses thwart this description; they are solids with liquid structure. The nature of the “glass transition” and why some materials form glasses more easily than others are deep mysteries that frustrate physicists. The atomic-scale structures that allow glasses to deform and are responsible for their Achilles’ heel of shear banding and brittle failure are not known. Empirical progress on this front is stymied by the lack of a routine method for characterising disordered structures. The lack of knowledge and understanding of the structure of glasses is a major road-block for glass science and technology.

A series of new and measureable structural parameters for glasses has recently been demonstrated by Monash University researchers [1,2,3]. This project will further test these new parameters on a series of metallic and silicate glasses to determine what role, if any, structure plays in properties such as glass-forming ability and mechanical response. The project will involve electron diffraction measurements on a next-generation scanning- transmission electron microscope with a low-noise, fast read-out rate direct electron detector (UltraTEM – installation in the Monash Centre for Electron Microscopy scheduled for late 2019). There will be opportunities for interactions with Prof. Kiyonori Suzuki (Materials Science and Engineering, Monash University), Dr Daniel East (CSIRO, Lab22) and collaborators at the University of Adelaide and Ames Laboratory, Iowa.

The project would suit a student interested in experimental materials physics and developing new data analysis tools.

References

[1] A. C. Y. Liu, M. J. Neish, G. Stokol, G. A. Buckley, L. A. Smillie, M. D. de Jonge, R. T. Ott, M. J. Kramer, and L. Bourgeois, Phys. Rev. Lett. 110, 205505, (2013)

[2] A. C. Y. Liu, R. F. Tabor, L. Bourgeois, M. D. de Jonge, S. T. Mudie, and T. C. Petersen, Phys. Rev. Lett., 116, 205501 (2016)

[3] A. C. Y. Liu, R. F. Tabor, M. D. de Jonge, S. T. Mudie, and T. C. Petersen, Proc. Nat. Acad. Sci., 114, 10344–10349, (2017)

Imaging Physics,
Condensed Matter Physics
Dr Amelia Liu

Simulating the explosions of massive stars

Core-collapse supernovae mark the death of massive stars: In an evolved star that has gone through the various burning stages, its iron core eventually collapses, leaving behind a neutron star, while the envelope is expelled in a violent and very bright explosion. These explosions are fascinating laboratories for matter under extreme conditions and cosmic furnaces that make many of the chemical elements that are the building block of planets like ours. Supernovae are also promising sources of neutrinos and gravitational waves, messengers that come directly from the innermost few hundreds kilometres of the collapse star and could allow us a direct glimpse at the supernova engine once such an explosion occurs within our Milky Way.

It has only recently become possible to successfully simulate such supernova explosions in three dimensions based on first principles. Many questions about these phenomena are still not fully unanswered: What makes supernovae explode? How do the explosion energy, the remnant mass, and the composition of the ejecta depend on the progenitor? Do some supernovae produce the heavy neutron-rich elements (like gold and the actinides)? Which progenitors form black holes? How do extremely energetic “hypernovae” come about?

Understanding these explosions requires sophisticated simulation codes. In this project, you will have the opportunity to contribute to a state-of- the-art relativistic radiation hydrodynamics code that has been successfully used model 3D supernova explosion driven by neutrino heating. Depending on your abilities and inclinations, you will add/improve modules to better treat the (magneto-)hydrodynamics, the radiation transport, or the neutrino and nuclear physics in the code. This will prepare you to solve some of the many open problems that current supernova simulations still face.

Students interested in high-performance computing will acquire first-hand experience with modern supercomputers during the course of their PhD. This is a computational project suited for students with a background in astronomy, applied mathematics, or nuclear/particle physics. Experience with computational fluid dynamics is advantageous.

For inquiries, please contact Dr Bernhard Mueller (bernhard.mueller@monash.edu).

Astronomy & Astrophysics Dr Bernhard Mueller

Single Shot X-ray Tomography for Real-Time 4D Functional Imaging

X-ray imaging can provide high resolution imagery of bodily organs in two and three dimensions (2D and 3D). 4D imaging is also possible, but only for slowly moving objects [1]. However, for extra dimension massively increases the ionizing radiation dose to the patient. Contrast in X-ray imaging relies on differential absorption of X-rays as they pass through materials of different chemical composition. A large fraction of the X-rays are Compton scattered at random angles to the incident beam direction. These create a problematic source of noise to X-ray images that greatly reduces image contrast and resolution. There are several methods employed in the clinic to remove these scattered photons to enhance image quality.

We have patented a technique to use the Compton scattered radiation as a source of information about the sample. We have shown that it is theoretically possible to quantitatively reconstruct the 3D structure of an object from a single short exposure. By taking multiple exposures as the object moves should enable 4D imagery with potentially very low radiation dose. For this project the student will work with our team to develop a robust image reconstruction algorithm and validate our theory using experimental data to be acquired at the Australian Synchrotron. The major benefits expected from this research are the potential for substantial dose reduction and real-time 4D imaging.

References

[1] Fouras A, Kitchen MJ, Dubsky S, Lewis RA, Hooper SB, Hourigan K, "The past, present and future of x-ray technology for in vivo imaging of function and form", Journal of Applied Physics, volume 105, issue 1 (2009).

Imaging Physics Associate Professor Marcus Kitchen

Study of Flavour Anomalies

An important component of particle physics research is the study of rare processes in `flavour physics’. In current experiments this typically refers to decays of bottom mesons that have very small branching fractions. Recent experimental studies of these decays have produced a number of `anomalies’, or disagreements with the standard model expectations.

In this project we will study these anomalies from the theoretical perspective, looking for common threads that can lead to global explanations in terms of new physics. When good explanations are found, they also produce predictions for upcoming experiments that can rule them out (or, with much luck, confirm them).

Particle Physics Professor German Valencia

The origin of matter

Various extensions of the Standard Model (SM) of fundamental particles have the potential to explain the origin of all matter in the Universe, baryonic (visible) and non-luminous (dark) matter alike. Unfortunately, we are missing key pieces of information: the global feasibility of these theories and their precise matter abundance predictions. The main reason for the latter is that, while several automated tools exist for the calculation of dark matter abundance, the generic techniques to calculate the baryon abundance are lagging behind.

The Monash Particle Phenomenology Group, together with the Global And Modular Beyond-the-SM Inference Tool (GAMBIT) international collaboration, are working on remedying this problem. For simplicity, we are focusing on electroweak baryogenesis, a promising and relatively easily falsifiable mechanism proposed to generate baryons in the early Universe. While GAMBIT is gearing up to calculate the feasibility of many SM extensions, the Monash group is creating robust and precise calculational techniques for electroweak baryogenesis.

In this project, we examine the calculation of cosmic baryon abundance in the context of electroweak baryogenesis in a particle model independent context. Where necessary, we develop new analytical methods to solve parts of the problem. These methods will then be used to create numerical algorithms (partly) by auto-generation of computer code. This project requires a solid background in particle physics, cosmology and excellent analytical and/or numerical proficiency. Insight into other areas of physics, such as thermal field theory, is useful.

Particle Physics Professor Csaba Balazs