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arXiv · 2010.07083

Magnetization relaxation and search for the magnetic gap in bulk-insulating V-doped (Bi, Sb)$_2$Te$_3$

E. Golias·E. Weschke·T. Flanagan·E. Schierle·A. Richardella·E. D. L. Rienks·P. S. Mandal·A. Varykhalov·J. Sánchez-Barriga·F. Radu·N. Samarth·O. Rader
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Abstract

V-doped (Bi,Sb)$_2$Te$_3$ has a ten times higher magnetic coercivity than its Cr-doped counterpart and therefore is believed to be a superior system for the quantum anomalous Hall effect (QAHE). The QAHE requires the opening of a magnetic band gap at the Dirac point. We do not find this gap by angle-resolved photoelectron spectroscopy down to 1 K. By x-ray magnetic circular dichroism (XMCD) we directly probe the magnetism at the V site and in zerofield. Hysteresis curves of the XMCD signal show a strong dependence of the coercivity on the ramping velocity of the magnetic field. The XMCD signal decays on a time scale of minutes which we conclude contributes to the absence of a detectable magnetic gap at the Dirac point.

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E. Golias, E. Weschke, T. Flanagan, E. Schierle, A. Richardella, E. D. L. Rienks, P. S. Mandal, A. Varykhalov, J. Sánchez-Barriga, F. Radu, N. Samarth, O. Rader. 2020-10-14. Magnetization relaxation and search for the magnetic gap in bulk-insulating V-doped (Bi, Sb)$_2$Te$_3$. https://doi.org/10.1063/5.0070557

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