Prediction of Near-Room-Temperature Quantum Anomalous Hall Effect on Honeycomb Materials.

(arXiv:1405.4731v1 [cond-mat.mtrl-sci])

Authors: Shu-chun Wu, Guangcun Shan, Binghai Yan

Recently, this long-sought quantum anomalous Hall effect was realized in the
magnetic topological insulator. However, the requirement of an extremely low
temperature (approximately 30~mK) hinders realistic applications. Based on
textit{ab-initio} band structure calculations, we propose a quantum anomalous
Hall platform with a large energy gap of 0.34 and 0.06 ~eV on honeycomb
lattices comprised of Sn and Ge, respectively. The ferromagnetic order forms in
one sublattice of the honeycomb structure by controlling the surface
functionalization rather than dilute magnetic doping. Strong coupling between
the inherent QSH state and ferromagnetism results in considerable exchange
splitting and consequently an FM insulator with a large energy gap. The
estimated mean-field Curie temperature is 243 and 509 K for Sn and Ge lattices,
respectively. The large energy gap and high Curie temperature indicate the
feasibility of the QAH effect in the near-room-temperature and even
room-temperature regions.

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