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The inquiry into topological materials has recently mingled with the quest for low-dimensional magnets, giving birth to an emerging frontier known as magnetic topological insulators where a topologically nontrivial band gap is controllable by spontaneous magnetic ordering. For example, an even layer MnBi2Te4 is a Chern insulator when a finite magnetization is established below the critical temperature while it is an axion insulator in the antiferromagnetic ground state. In the first part, we show that thermal spin fluctuations disturbing the magnetization can act as frozen disorders that strongly scatter electrons, reducing the onset temperature of quantized transport appreciably even in the absence of structural impurities. On the other hand, although some transport experiments have hinted at its existence, the axion insulator phase in the ground state yet remains elusive. In the second part, we propose a MnBi2Te4 tunnel junction to unambiguously confirm the axion insulator phase by using the quantized magnetoelectric effect.
References:
[1]. Yu-Hang Li and Ran Cheng, Physical Review Letters 126, 026601(2021)
[2]. Yu-Hang Li and Ran Cheng, Physical Review Research 4, L022067(2022)
Yuhang Li is currently a postdoc scholar in the University of California at Riverside. After graduated from Sichuan University in 2013, he earned his PhD from Peking university in 2018. Since 2019, he has been a postdoc scholar in the University of California at Riverside. His research interests focus on quantum transport, spintronics, magnetism, and topological superconductors.
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