Mesoscopic correlated electron and topological physics

In recent years it has become possible to use focused ion beam and electron beam techniques to bring ultrapure single crystals of novel correlated electron and topological materials into mesoscopic regimes in which the sample size is similar to one or more of the characteristic length scales (e.g. mean free path, magnetic length, superconducting coherence length or penetration depth) that define their physics [1]. Importantly, our group has demonstrated that this can be done without significant damage to the bulk of the miniaturised samples [2]. This is largely unexplored territory; although the physics promises to be extremely exciting, it requires a substantial investment in equipment in order to be competitive.  At MPI CPfS we have made such an investment, and have just commissioned a comprehensively equipped clean room specially designed for this class of research. We will be offering a number of projects in this area, covering investigation of topological effects in metals [3], hydrodynamic and ballistic electronics, unconventional superconductivity, ionic liquid gating of semiconductors and insulators, and more. We will also use our microstructuring techniques to miniaturise uniaxial pressure experiments and combine those new techniques with the above physics themes. There will also be opportunities to perform research close to chemistry, since the starting materials need not be crystals grown from a liquid but could be crystallites from samples prepared using solid state chemical routes. New clean rooms have also been built in St Andrews, offering the possibility of collaborative research and interchange of expertise and ideas. 

[1] P.J.W. Moll, R. Puzniak, F. Balakirev, K. Rogacki, J. Karpinsky, N.D. Zhigadlo and B. Batlogg
High magnetic-field scales and critical currents in SmFeAs(O, F) crystals
Nature Materials 9, 628 (2010)
[2] P.J.W. Moll, P. Kushwaha, N. Nandi, B. Schmidt, A.P. Mackenzie
Evidence for hydrodynamic electron flow in PdCoO2
Science 351, 1061 (2016)
[3] P.J.W. Moll, N.L. Nair, T. Helm, A.C. Potter, I. Kimchi, A. Vishwanath and J.G. Analytis
Transport evidence for Fermi-arc-mediated chirality transfer in the Dirac semimetal Cd3As2
Nature 535, 266 (2016)

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