ÌÇÐÄTV

Are you interested in being at the forefront of understanding new electronic and
magnetic properties?

High magnetic fields have long been used to characterise the behaviour of spins and electrons in magnets, metals, semiconductors and superconductors. However, in recent years new materials have emerged that challenge our existing understanding of magnetic and electronic behaviour. New theoretical models are required to explain the properties displayed by these so-called quantum materials, which are typically host to complex networks of many- body interactions between spins and electrons, and are exquisitely sensitive to aspects such as dimensionality, fluctuations and topology. In this project we will collect experimental data that will be used to develop and test evolving theories of novel electronic and magnetic properties. Promising avenues include:

(a) Crystal structure showing layers of Fe₃GeTe₂ coupled by weak vdW bonds [2]. (c) Quantum oscillations observed in CeOs₄Sb₁₂ [3]. (c) Angle-dependent magnetoresistance measurements of a high-temperature superconductor performed at 45 T and 20 K [4].

A new route to quantum spin liquids.

Topological behaviour arises in many areas of research, from quantum-Hall physics to band structure, defects in crystalline lattices, and magnetism, and impacts many areas of technological relevance (e.g., spintronics, data storage and quantum technologies in general). While spin liquids arising from frustrated magnetism have shown to be been fertile ground for exploring topological effects, so far they emerge only within narrow regions of physical phase diagrams, limiting their robustness and practical applicability. It was recently shown that similar behaviour should be found in materials in which the hopping of itinerant electrons is frustrated [4]. This paves the way for a completely new route for the experimental realisation of quantum spin liquids based on kinetic rather than geometric frustration of interactions – a route that requires further theoretical and, importantly, experimental investigation. Measuring magnetic and electronic properties in candidate materials will be invaluable in understanding these new states.

Anomalous quantum oscillations.

Oscillations in the physical properties of materials subject to a changing magnetic field are known to be a hallmark of metallic materials. Recently, however,
these quantum oscillations have been observed in a number of apparently insulating materials. A
host of theories have emerged to account for these results, but no clear picture has so far emerged
likely due to to a lack of systematic, high-quality experimental data. We will investigate a number
of different materials to attempt to resolve this fast-developing mystery.

By exploring these new avenues, we hope to push our understanding beyond the current limits and open a route for exploiting the untapped potential of new quantum materials to underpin future technology. High magnetic fields will be accessed using in-house apparatus and by travelling to facilities that provide the world’s highest available fields, such as the European Magnetic Field Laboratory and the National High Magnetic Field Laboratory in the US.

Prof Goddard joined ÌÇÐÄTV University in 2013 and is expert in the use of high magnetic fields to elucidate the properties of new materials of fundamental and technological significance. In 2023, he was awarded the Pippard Prize by the Superconductivity Group of the Institute of Physics for his developmental work on the technique of angle-dependent magnetoresistance.

‘2D’ materials like graphene and transition metal dichalcogenides (TMDs) possess a rich array of electronic properties, from superconductivity to non-trivial band topology. Their ‘2D’ nature originates from their weak bonding along the c-axis, which allows for the isolation of large-area monolayer sheets. Dissimilar monolayers can then be recombined to create artificial heterostructures with rare electronic properties desirable for next-generation applications. Very recently, a new method of heterostructure engineering was identified that allows one to simply create new hybrid materials in the three-dimensional limit, which exhibit electronic band dispersions in k_z, as well as k_x and k_y.

A 3.5-year PhD studentship is available starting from October 2026 to use these new methods to engineer artificial magnetic heterostructures. This is a joint studentship between the University of ÌÇÐÄTV and Diamond Light Source (DLS), the UK’s national synchrotron facility based in Oxfordshire. In the first part of the project, under the supervision of Prof. Geetha Balakrishnan at the University of ÌÇÐÄTV, layered single crystals with magnetic properties will be grown and characterized in the state-of-art laboratories at ÌÇÐÄTV. The second part will be based at the i05 and i09 beamlines of DLS, where these layered magnets will be thinned down and incorporated into simple two-component heterostructures alongside other layered materials.

This approach could drive the overlap of exotic materials properties that do not normally coexist. For example, the combination of a layered 2D magnet like CrGeTe₃ and a topological metal like NiTe₂ could produce a topological magnet exhibiting anomalous quantum Hall effects. The electronic and magnetic properties of both the raw single crystal materials and the artificial heterostructures will be characterised using angle-resolved photoemission spectroscopy (ARPES) at DLS and occasionally at other international synchrotron facilities in the EU and USA.

This is an open-ended, ambitious project but with well-defined milestones and outcomes, suited for a strong and enthusiastic student.

Magnetic phenomena in materials are among the earliest scientific discoveries and remain some of the most technologically significant. Despite this, the understanding of topological magnetism is relatively recent and continues to evolve rapidly, with key discoveries in physics, materials, and potential applications. Topological magnetic systems exhibit a range of promising properties and excitations [1–3]. Various topological objects—such as domain walls and, more recently, skyrmions—are already known in magnetic materials. Moreover, other exotic structures, including hopfions, blochions, and merons, have also been stabilised. The discovery of these topological spin textures and their potential as high-density, low-energy components for magnetic storage and computational technologies has established topological magnetism as a major focus of condensed matter research.

Real-space schematics of the incommensurate spin textures investigated in this study, illustrating variations in the propagation direction (q), net electric polarisation (ΣP), and their relative orientation to the applied magnetic field [4].

In this PhD studentship, the student will synthesise crystals of novel bulk topological magnetic systems using a range of methods. Detailed investigations of the materials’ structural and magnetic properties will be conducted in-house. Additionally, X-rays, neutrons, and muons at international facilities will be employed to explore the topological properties of these novel magnetic systems.

This is a dynamic and rapidly evolving field, providing an excellent opportunity for a motivated and capable student to engage in cutting-edge research.This project will draw upon the University of ÌÇÐÄTV’s expertise in single-crystal growth and characterisation within the Superconductivity and Magnetism Group. It will offer the student comprehensive training in magnetism and, more broadly, in condensed matter physics.