Correlated Electron Physics of Delafossite Oxide Metals

Strong electronic correlations underpin some of the most fascinating, yet still poorly understood, phenomena in solid-state physics. Delafossite-oxide metals show enormous promise for exploring new physics governing the behavior of such correlated electrons in solids, and their interplay with itinerant carriers. Existing measurements reveal these compounds to host a particularly wide array of intriguing materials properties, from ultra-high conductivity [1,2,3] to unconventional magnetism [4], and the potential to host strongly spin-orbit coupled states at their surfaces and interfaces [5].

In this project, you will work in MPI-CPFS Dresden to perform single-crystal growth and/or transport studies of new delafossite oxides. The key aim is to demonstrate and understand strong correlation physics of their transition-metal-oxide structural building blocks which, excitingly, support a triangular-lattice arrangement of the transition metals. You will study the resulting bulk and surface electronic structure of these crystals using angle-resolved photoemission spectroscopy (ARPES) performed at synchrotron light sources and using a state-of-the-art laboratory set-up in St Andrews. Through this, you will aim to uncover and disentangle the influence of many-body interactions on the electronic structure of delafossites, and how these evolve through (bulk and surface) doping, aiming to gain new insight into the quantum many-body problem in solids.  

This project would suit a talented student with a background in solid state or materials physics who is interested in combining materials synthesis with advanced experimental measurements and data analysis. You will spend part of your time performing research in MPI CPfS Dresden, part in St Andrews, and will also undertake experiments at national and international facilities. Thus, a willingness to travel is an essential prerequisite.

Example of an ARPES measurement on the delafossite material PdCoO2
[1] P. Kushwaha, V. Sunko, P.J.W. Moll, L. Bawden, J.M. Riley, N. Nandi, H. Rosner, M.P. Schmidt, F. Arnold, E. Hassinger, T.K. Kim, M. Hoesch, A.P. Mackenzie, and P.D.C. King
Nearly free electrons in a 5d delafossite oxide metal
Science Advances 1, 1500692 (2015)
[2] P.J.W. Moll, P. Kushwaha, N. Nandi, B. Schmidt, A.P. Mackenzie
Evidence for hydrodynamic electron flow in PdCoO2
Science Magazine, 351(6277), 1061–1064 (2016)
[3] N. Nandi, T. Scaffidi, P. Kushwaha, S. Khim, M.E. Barber, V. Sunko, F. Mazzola, P.D.C. King, H. Rosner, P.J.W. Moll, M. König, J.E. Moore, S. Hartnoll, and A.P. Mackenzie
Unconventional magneto-transport in ultrapure PdCoO2 and PtCoO2
npj Quantum Materials 3, 66 (2018)
[4] A.P. Mackenzie
The properties of ultrapure delafossite metals
Rep. Prog. Phys. 80, 032501 (2017)
[5] V. Sunko, H. Rosner, P. Kushwaha, L. Bawden, O.J. Clark, J.M. Riley, D. Kasinathan, M.W. Haverkort, T.K. Kim, M. Hoesch, J. Fujii, I. Vobornik, A.P. Mackenzie, and P.D.C. King
Maximal Rashba-like spin splitting via kinetic-energy-coupled inversion-symmetry breaking
Nature 549, 492 (2017)

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