Intrinsic quantized anomalous Hall effect in a moiré heterostructure

2019/06/29 by M. Serlin, C. L. Tschirhart, H. Polshyn +6 · 3 citations
Physics and Astronomy · #cond-mat.str-el #cond-mat.mes-hall #cond-mat.mtrl-sci

paper · pdf · doi:10.1126/science.aay5533

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arxiv created 2019/06/29 · arxiv updated 2020/03/18

Abstract

We report the observation of a quantum anomalous Hall effect in twisted bilayer graphene showing Hall resistance quantized to within .1% of the von Klitzing constant h/e² at zero magnetic field.The effect is driven by intrinsic strong correlations, which polarize the electron system into a single spin and valley resolved moiré miniband with Chern number C=1. In contrast to extrinsic, magnetically doped systems, the measured transport energy gap Δ/k_B≈ 27~K is larger than the Curie temperature for magnetic ordering T_C≈ 9~K, and Hall quantization persists to temperatures of several Kelvin. Remarkably, we find that electrical currents as small as 1~nA can be used to controllably switch the magnetic order between states of opposite polarization, forming an electrically rewritable magnetic memory.

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