Abstract:

Dissipationless  transport  of  charge  is  one  of  the  most  consequential  manifestations  of quantum mechanics on macroscopic scales. It is an essential property of two remarkable states of quantum matter: superconductivity and quantized Hall effects. The first state emerges from strong  electron  correlations  and  the  second  from  nontrivial  band  topology  ─  both  extremely challenging  to  unpack  on  a  fundamental  level  and  both  with  a  tremendous  technologically-transformative  potential  in  energy  transfer,  quantum  information  processing,  and  quantum electronics. It has been proposed not long ago that quantum anomalous Hall (QAH) state near the plateau transition and in proximity to a fully gapped s-wave superconductor may realize achiral topological superconducting state that can carry Majorana zero modes responsible for the non-Abelian statistics of vortices required for fault-tolerant quantum computing. Here I will describe a previously unknown Berry-curvature-driven QAH regime at temperatures of several Kelvin we uncovered in the magnetic topological bulk crystals in which Mn ions self-organize into a period-ordered  MnBi2Te4/Bi2Te3 superlattice[1]. Robust out-of-plane ferromagnetismof the MnBi2Te4 layers opens a surface gap, and when the Fermi level is tuned to be within this gap, the anomalous Hall conductance reaches an e2/h quantization plateau, which is a clear indication of dissipationless chiral currents through the edge states.The eminently tunable topological electronic band structure of this system by the high energy electron beams [2] and thermal redistribution of vacancies may lead to a room-temperature lossless conduction of charge and may provide a realistic platform for chiral superconducting state.

[1] H. Deng, Z. Chen, A. Wołoś, M. Konczykowski, K. Sobczak, J. Sitnicka, I.V. Fedorchenko, J. Borysiuk, T. Heider, Ł. Pluciński, K. Park, A.B. Georgescu, J. Cano, and L. Krusin-Elbaum, Nature Phys. (2020); doi.org/10.1038/s41567-020-0998-2.

[2] L. Zhao, M. Konczykowski, H. Deng, I. Korzhovska, M. Begliarbekov, Z. Chen, E. Papalazarou, M. Marsi, L. Perfetti, A. Hruban, A. Wołoś, and L. Krusin-Elbaum, Nature Comm. 7, 10957 (2016).

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