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arXiv · 2505.00117

Interlayer Coupling-Induced Quantum Phase Transition in Quantum Anomalous Hall Multilayers

Ling-Jie Zhou·Deyi Zhuo·Ruobing Mei·Yi-Fan Zhao·Kaijie Yang·Ruoxi Zhang·Zijie Yan·Han Tay·Moses H. W. Chan·Chao-Xing Liu·Cui-Zu Chang
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Abstract

A quantum phase transition arises from competition between different ground states and is typically accessed by varying a single physical parameter near absolute zero temperature. The quantum anomalous Hall (QAH) effect with high Chern number C has recently been achieved in magnetic topological insulator (TI) multilayers. In this work, we employ molecular beam epitaxy to synthesize a series of magnetic TI penta-layers by varying the thickness of the middle magnetic TI layer, designated as m quintuple layers. Electrical transport measurements demonstrate a quantum phase transition between C = 1 and C = 2 QAH states. For m 1 and m 2, the sample exhibits the well-quantized C = 1 and C = 2 QAH states, respectively. For 1 m 2, we observe a monotonic decrease in Hall resistance from h/e2 to h/2e2 with increasing m, accompanied by a peak in the longitudinal resistance. The quantum phase transition between C = 1 and C = 2 QAH states is attributed to the weakening of the interlayer coupling between the top and the bottom C = 1 QAH layers. Our findings provide a scalable strategy for engineering QAH devices with a tunable Chern number. This approach enables precise control and enhanced functionality in chiral edge current-based electronic devices.

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Ling-Jie Zhou, Deyi Zhuo, Ruobing Mei, Yi-Fan Zhao, Kaijie Yang, Ruoxi Zhang, Zijie Yan, Han Tay, Moses H. W. Chan, Chao-Xing Liu, Cui-Zu Chang. 2025-04-30. Interlayer Coupling-Induced Quantum Phase Transition in Quantum Anomalous Hall Multilayers. https://doi.org/10.1103/physrevb.111.l201304

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