Berlin 2024 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 29: Quantum Transport and Quantum Hall Effects
HL 29.1: Invited Talk
Wednesday, March 20, 2024, 09:30–10:00, EW 561
Nonreciprocal charge transport on the edges of a quantum anomalous Hall insulator — •Gertjan Lippertz1,2, Anjana Uday1, Andrea Bliesener1, Lino Pereira2, Alexey Taskin1, and Yoichi Ando1 — 1Physics Institute II, University of Cologne, Cologne, Germany — 2Quantum Solid State Physics, KU Leuven, Leuven, Belgium
The quantum anomalous Hall insulator (QAHI) is characterized by a zero longitudinal resistivity and a quantized Hall resistance without the need of an external magnetic field. However, when reducing the device dimensions or increasing the current density, an abrupt breakdown of the dissipationless state occurs. We have previously proposed that this breakdown originates from the electric-field-driven percolation of charge puddles in the 2D bulk states of the compensated thin film [1]. It was recently reported that the interplay between the 1D chiral edge state and the 2D bulk states in a QAHI can give rise to nonreciprocal charge transport [2]. So far, this nonreciprocity was only studied in the broken-down QAHI state at elevated temperatures and at high excitation currents [2], and hence its emergence from the low-current, dissipationless regime remains to be understood. In this talk, we show that the onset of 2D bulk conduction due to breakdown is sufficient to create the nonreciprocal effect, and interestingly, there is a sign change in the nonreciprocity with increasing current, suggesting a crossover in the underlying mechanism of the nonreciprocal transport.
[1] Lippertz et al., Phys. Rev. B 106, 045419 (2022)
[2] Yasuda et al., Nat. Nanotechnol. 15, 831-835 (2020)
Keywords: quantum anomalous Hall effect; magnetic topological insulator; nonreciprocal charge transport