Zhang Peng, Balakrishnan Purnima P, Eckberg Christopher, Deng Peng, Nozaki Tomohiro, Chong Su Kong, Quarterman Patrick, Holtz Megan E, Maranville Brian B, Qiu Gang, Pan Lei, Emmanouilidou Eve, Ni Ni, Sahashi Masashi, Grutter Alexander, Wang Kang L
Department of Electrical and Computer Engineering, University of California Los Angeles, Los Angeles, CA, 90095, USA.
NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, 20899-6102, USA.
Adv Mater. 2023 Aug;35(31):e2300391. doi: 10.1002/adma.202300391. Epub 2023 Jun 27.
The quantum anomalous Hall (QAH) effect is characterized by a dissipationless chiral edge state with a quantized Hall resistance at zero magnetic field. Manipulating the QAH state is of great importance in both the understanding of topological quantum physics and the implementation of dissipationless electronics. Here, the QAH effect is realized in the magnetic topological insulator Cr-doped (Bi,Sb) Te (CBST) grown on an uncompensated antiferromagnetic insulator Al-doped Cr O . Through polarized neutron reflectometry (PNR), a strong exchange coupling is found between CBST and Al-Cr O surface spins fixing interfacial magnetic moments perpendicular to the film plane. The interfacial coupling results in an exchange-biased QAH effect. This study further demonstrates that the magnitude and sign of the exchange bias can be effectively controlled using a field training process to set the magnetization of the Al-Cr O layer. It demonstrates the use of the exchange bias effect to effectively manipulate the QAH state, opening new possibilities in QAH-based spintronics.
量子反常霍尔（QAH）效应的特征是在零磁场下具有量子化霍尔电阻的无耗散手性边缘态。操控QAH态对于理解拓扑量子物理和实现无耗散电子学都非常重要。在此，在生长于未补偿反铁磁绝缘体Al掺杂Cr₂O₃上的磁性拓扑绝缘体Cr掺杂（Bi，Sb）₂Te₃（CBST）中实现了QAH效应。通过极化中子反射率（PNR），发现CBST与Al-Cr₂O₃表面自旋之间存在强交换耦合，该耦合使界面磁矩垂直于薄膜平面固定。这种界面耦合导致了交换偏置的QAH效应。该研究进一步表明，使用场训练过程来设定Al-Cr₂O₃层的磁化强度，可以有效地控制交换偏置的大小和符号。它展示了利用交换偏置效应有效地操控QAH态，为基于QAH的自旋电子学开辟了新的可能性。
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