High-precision observation of nonvolatile quantum anomalous Hall effect

Abstract

The discovery of the quantum Hall (QH) effect led to the realization of a topological electronic state with dissipationless currents circulating in one direction along the edge of a two-dimensional electron layer under a strong magnetic field[superscript 1, 2]. The quantum anomalous Hall (QAH) effect shares a similar physical phenomenon to that of the QH effect, whereas its physical origin relies on the intrinsic spin–orbit coupling and ferromagnetism[superscript 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]. Here, we report the experimental observation of the QAH state in V-doped (Bi,Sb)[subscript 2]Te[subscript 3] films with the zero-field longitudinal resistance down to 0.00013 ± 0.00007h/e[superscript 2] (~3.35 ± 1.76 Ω), Hall conductance reaching 0.9998 ± 0.0006e[superscript 2]/h and the Hall angle becoming as high as 89.993° ± 0.004° at T = 25 mK. A further advantage of this system comes from the fact that it is a hard ferromagnet with a large coercive field (H[subscript c] > 1.0 T) and a relative high Curie temperature. This realization of a robust QAH state in hard ferromagnetic topological insulators (FMTIs) is a major step towards dissipationless electronic applications in the absence of external fields.