2025/04/30 by Zhou, Ling-Jie, Zhuo, Deyi, Mei, Ruobing +8
#FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
paper · doi:10.48550/arxiv.2505.00117
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.