Category Archive

The memristor, a resistor with memory retention capability, is a newly discovered circuit element that is useful for non-magnetic non-volatile memory and logic operations for traditional computation. Additionally, it emulates short- and long-term plasticity of biological synapses, making it an ideal component for unconventional ultrafast neuromorphic (brain-inspired) computing. An ultrathin low-power memristor can be a strong candidate for replacing today’s …

In recent years, many concepts belonging to thermodynamics have been translated to quantum systems. While the description of such systems is often highly abstract, this project will explore some of these ideas in the context of physically realisable many-body quantum systems. Supervisor: A/Prof. Meera Parish and Dr Jesper Levinsen See https://www.monash.edu/science/schools/physics/honours/honours-project to apply.

Periodic driving of a system endows it with a temporal periodicity, much like crystal lattices that have a spatial periodicity. Yet, periodic driving yields a variety of tuning knobs which can in principle allow one to investigate physics that is difficult to access in any equilibrium system. Indeed, even though there is only one time dimension, one can even make …

There are numerous observations shedding light on the properties of dark matter, however its decomposition is unknown. Based on its known properties, we examine whether dark matter can be superfluid light. Our speculation is motivated by the recent observations of Bose-Einstein condensation of photons [1] and by the successes of the bosonic star dark matter models [2]. In this project, …

Topological insulators (TI) represent a new state of quantum matter. TIs have insulating bulk (like an ordinary insulator) and exotic metallic surface states. These states are described by a relativistic-like Dirac equation for massless particles that models their unconvenitional behaviour. In particular, the direction of electron spin for Dirac electron is perfectly correlated (or locked) with the direction of its …

Scanning tunnelling spectroscopy (STS), combined with scanning tunnelling microscopy (STM), is a powerful tool to explore a material’s electronic properties in real space, as it allows probing the local electronic density of states (DOS) with atomic resolution. STS can visualize spatial modulations of the electronic states, and capture collective phenomena like standing wave patterns originating from electrons scattering off defects. …

Superconductivity and superfluidity are macroscopic quantum phenomena that are observed at low temperatures. Bringing them to room temperatures is the Holy Grail in physics. One prospective system is a double layered semiconductor structure with spatially separated electrons and holes (holes are empty electronic states that can be treated as particles with positive charges). Attractive Coulomb interactions can bind them to …

Topological materials, like topological insulators and topological Weyl semimetals, are a new classes of matter with unusual electronic properties: Weyl semimetals have Weyl points in their bandstructures, around which electrons behave as massless chiral particles (similar to neutrinos). Topological insulators are insulators in the bulk but have highly conducting massless helical electrons on their surfaces or edges. One way to …

Weyl semimetals are new topological solids with protected massless Dirac electronic states in their bulk and exotic Fermi arc surface states. The electrodynamics of these materials have additional “axion” terms that can manifest as in transport as in optical phenomena and have attracted recently a lot of attention. The project is devoted to an analysis of a distribution of electric …

Atomically-thin transistors made by 2D semiconducting materials possess attractive electronic properties and have been seen as building blocks for next-generation semiconductor chips. This project aims to study the transport properties of 2D field-effect transistors, including carrier mobility and contact resistance. In particular, we will focus on optimising the metal-semiconductor junction. In other words, we will develop high-performance 2D transistors by …

The past couple of decades has seen a revolution in materials technology, the emergence of atomically thin materials. This was initiated by the discovery of graphene (2010 Nobel prize), but the field now comprises a range of different materials in the ultimate single-atom-thin limit. This project will focus on a particular class, the so-called transition metal dichalcogenides (TMDs), that possess …

Understanding the response of quantum matter to changes in the system parameters is crucial in developing new technologies. Recent advances in ultracold atomic gases have enabled the systematic study of the fastest collective response possible in any quantum system (relative to system density). Specifically, the low particle density and large atom mass compared with electrons in solids means that the …

Topological insulators are a class of materials which are electronically insulating in the bulk and highly conducting at the surface. These special surface states provide unique access to highly mobile spin-polarised electrons, which makes these materials a desirable component for future electronics. This project aims to create an ultraclean, protected environment for the surface states of the layered topological insulating …

Three-dimensional Dirac semi-metals such as Na3Bi are a new class of material where electrons behave as relativistic Dirac-like fermions, moving at constant velocity independent of energy, much like massless neutrinos. In the Fuhrer laboratory we utilize a low-temperature (4K) scanning tunnelling microscope (STM) equipped with a molecular beam epitaxy chamber to study Na3Bi grown under ultra-high vacuum conditions. The primary …

The one-dimensional Fermi gas with repulsive short-range interactions provides an important model of strong correlations in few- and many-particle systems. However, in the presence of a harmonic potential, no exact solution is known in general for strongly interacting fermions. We have recently shown that this problem in the regime of strong repulsion can be mapped onto a Heisenberg spin chain, …

Graphene – an atomically thin sheet of carbon atoms – has attracted enormous scientific interest since its discovery in 2003. Awarded with the Nobel Prize only seven years after it was discovered, the material was soon hailed as the next disruptive technology due to superior attributes, being a zero-band gap Dirac semi-metal with large electron mobility. A related class of …

Techniques for optically observing single molecules are extending and even changing our understanding of molecular processes in biology. Often, it is desirable to follow the dynamics of a single molecule for several seconds or longer. Methods have been developed to immobilize and isolate or confine single molecule in order to study their dynamics on such long time scales. One such …

Ultracold atoms can be trapped in an optical lattice, the periodic potential formed by optical standing waves. The atoms in the optical lattice exhibit behavior similar to electrons in an ideal crystal. By including the interaction of the atoms, such a system can be used to study many-body phenomena traditionally in the realm of solid-state physics. This project will investigate …

On-surface supramolecular chemistry – through which molecular and atomic units interact and form well-defined geometries – holds promise for the fabrication of nanostructures with atomic-scale precision and tailored electronic properties [1]. This project consists of using approaches of supramolecular chemistry to synthesise low-dimensional organic and metal-organic nano-assemblies on surfaces. The goal is to achieve solid-state interfaces with atomically precise morphologies, …

The interaction of light with matter invariable involves the exchange of momentum. This exchange of momentum can be exploited to trap and remotely manipulate particles from the size of individual atoms to objects at the micron scale. Typically, the study of optical forces on these vastly different size objects is performed independently. The purpose of this project is to investigate …

Supramolecular and metal-organic self-assembly on surfaces holds promise for the synthesis of functional low-dimensional nanostructures with ultimate atomic-scale precision [1]. 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 …

Fuhrer, Hellerstedt and Edmonds have developed unique-in-the-world techniques to measure the electrical properties, such as resistivity and Hall effect, of a thin film of material during growth by molecular bean epitaxy (MBE) as well as post-growth without removing the sample from vacuum. This allows for studies of exotic materials that may be unstable on removal from vacuum. The current techniques …

The change of electrical resistance in a magnetic field (i.e., the magetoresistance) is typically rather small in many materials, but it can have important technological applications when it is sizeable. For instance, the “giant magnetoresistance ” of magnetic multilayer structures provides the basis for magnetic sensors used in hard disks and other devices. However, magnetism is not the only route …

Topological insulators are a novel class of materials with non-trivial electronic properties. Electrons at the boundaries of these materials can propagate without dissipating energy [1]. So far, topological phases have only been demonstrated in inorganic materials. The goal of this project is to synthesise and characterise low-dimensional organic nanostructures, in which the atomic-scale morphology and electronic structure give rise to …

Topological materials, such as topological insulators and topological Dirac semimetals, are a new class of matter that possess new and exciting electronic properties. Allowing a wide range of new physics to be explored including Majorana fermions and the Chiral anomaly to create revolutionary new electronic devices that have the potential to transport charge through one-dimensional edge modes without dissipation. In …

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 …

The cell is a crowded environment where complex chemical reactions take place, typically involving only a few numbers of molecules. While a number of these reactions have been studied in bulk assays or even at the single molecule level, the role of crowded environment or confinement has typically not been investigated. The goal of this project is to study the …

Atomtronics is an emerging research area that seeks to develop devices that will exploit the unique properties of ultracold atoms to deliver benefits over conventional technologies. Potentials based on optical fields are currently used to manipulate and pattern ultracold atoms, which limits feature sizes to the wavelength of light. This project would investigate potentials for ultracold atoms based on atom-atom …

Recently new materials have emerged in which the electron dynamics are described by the Dirac equation in two dimensions. An example is graphene, the two-dimensional honeycomb lattice of carbon atoms that is the basic building block of graphite. In graphene, the electrons obey a massless Dirac equation, with the role of the relativistic electron spin played by a spinor (“pseudospin”) …

Atomically thin semiconductors, materials comprised of surface only, have remarkable electronic and optical properties and allow us to study basic physical concepts in a well-controlled environment. Besides this, these materials are envisioned to be used in future types of electronics, making them attractive for both basic and applied research. In 2D semiconductors, donor impurities (ions) and their bound electron, as well …

The development of ultracold atomic gases with tunable interactions and dimensionality has led to a new era of precision studies of fundamental quantum mechanical phenomena. In the context of few-body bound states, experiments have until now focussed on bosons, which display the celebrated Efimov effect, where three identical bosons can form a fractal set of states related by a discrete …

Hybrid organic-inorganic perovskites are an emerging class of photovoltaic materials with the potential to outperform silicon [1]. Solar cells made of metal-halide perovskite offer material costs below $2/m2 and certified 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 …

Two-dimensional turbulence is even more fascinating than its three-dimensional counterpart. Here, the turbulent energy is predicted to go into the formation of increasingly larger size eddies and vortices in a so-called inverse energy cascade process. Hence 2D turbulence exhibits a peculiar self-organization, giving rise to order out of chaos. This project will involve investigating two-dimensional turbulence in a superfluid atomic …