Quantum Materials and Magnetism
This area is concerned with the study of materials with complex electronic order, of which popular examples are superconductors and magnetic materials. Research in this field is fast moving and exciting because of its impact on both fundamental understanding and applications. The group at Kent is interdisciplinary and includes 10 academics, with complementary interests and expertise. Together we cover all the main aspects of fundamental research in this area: the synthesis of new materials, the characterization of their bulk and microscopic properties, the computer simulations and the theory to explain and predict these properties.
Synthesis (Arnold, Green, McCabe): this work currently includes functional oxide materials that combine magnetic and ferroelectric properties to form novel multiferroic materials and mixed anion systems that display complex electronic behavior, such as the oxypnictides and the oxychalcogenides.
Characterisation (Arnold, Green, McCabe, Pugh, Ramos): the group makes use of the comprehensive facilities at Kent for sample characterization (XRD, Raman, SEM, SQUID, transport measurements at low temperatures and high pressures, etc.) but also is has an international reputation for the work carried out a large facilities, using mainly X-rays and neutrons to study atomic and electronic structure of strongly correlated materials. The topics of interest in our group include magnetic materials, superconductors, quantum critical behavior and quantum phase transitions, multiferroics, and topological insulators.
Fig. 1: FMG PhD students Sinead Rowe and Ben Coles at Diamond Light Source
Fig. 2: Refined structure and XANES measurements of La1-xCaxMnO2+δ (0.6 < x < 1). The low temperature reduction of the La1-xCaxMnO3 perovskite phases with sodium hydride results in the formation of these materials, where Mn(I) centers can be found in an extended oxide framework (E. Dixon, J. Haderman, S. Ramos, A.L. Goodwin, M.A. Hayward, JACS 133, 18397, 2011)
Simulation and Theory (Alfredsson, Bristowe, Carr, Möller, Quintanilla, Strange): We have a very active group of theorists working on a broad range of topics using many complementary approaches. Some overarching themes of our research are: relativistic quantum-mechanical effects (e.g. spin-orbit coupling) in rare earths and superconductors; topological aspects of condensed matter physics; light-matter interactions; ferroic complex oxides and their interfaces; and new quantum phases of matter. The methods range from first-principles simulations, which can describe the electronic structure of particular materials in great detail, to work carried out on more simplified models to which one can apply advanced techniques of quantum many-body theory (from exact solutions via field theory to more computational approaches such as diagrammatic Monte Carlo and tensor networks). We often work very closely with experimentalists, where a model-independent approach based on general considerations, such as symmetry analyses, often fits best.