<p>Realizing the quantum anomalous Hall effect (QAHE) at high temperatures remains a significant challenge in condensed matter physics. MnBi<sub>2</sub>Te<sub>4</sub>, an intrinsic magnetic topological insulator, presents a promising platform for QAHE. However, its inherent interlayer antiferromagnetic coupling hinders practical realization at high temperatures. In this study, we propose a novel approach to achieve interlayer ferromagnetic (FM) coupling in MBT bilayer by intercalating the septuple-layer of topological insulators XBi<sub>2</sub>Te<sub>4</sub> (X=Ge, Sn, Pb). Using first-principles calculations, we demonstrate that the <i>p</i><sub><i>z</i></sub> orbital of the X atom mediates interactions between interlayer Mn atoms, enabling FM coupling. Monte Carlo simulations predict a magnetic transition temperature of 38 K for the MnBi<sub>2</sub>Te<sub>4</sub>/PbBi<sub>2</sub>Te<sub>4</sub>/MnBi<sub>2</sub>Te<sub>4</sub> heterostructure. Our band structure and topological analyses confirm the preservation of QAHE in all MnBi<sub>2</sub>Te<sub>4</sub>/XBi<sub>2</sub>Te<sub>4</sub>/MnBi<sub>2</sub>Te<sub>4</sub> heterostructures, while the MnBi<sub>2</sub>Te<sub>4</sub>/PbBi<sub>2</sub>Te<sub>4</sub>/MnBi<sub>2</sub>Te<sub>4</sub> heterostructure exhibits a topological band gap of 72 meV, significantly exceeding that of the pure MnBi<sub>2</sub>Te<sub>4</sub> bilayer. Furthermore, a continuum model is developed to elucidate the underlying mechanism of the nontrivial topological states. Our work provides a practical pathway to achieving interlayer FM coupling in MnBi<sub>2</sub>Te<sub>4</sub> bilayers, paving the way for high-temperature QAHE and advancing the development of magnetic topological insulators for quantum and spintronic applications.</p>

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Septuple XBi2Te4 (X=Ge, Sn, Pb) intercalated MnBi2Te4 for realizing interlayer ferromagnetism and quantum anomalous hall effect

  • Ruixia Yang,
  • Xiaoxiao Man,
  • Jiahui Peng,
  • Jingjing Zhang,
  • Fei Wang,
  • Fang Wang,
  • Huisheng Zhang,
  • Xiaohong Xu

摘要

Realizing the quantum anomalous Hall effect (QAHE) at high temperatures remains a significant challenge in condensed matter physics. MnBi2Te4, an intrinsic magnetic topological insulator, presents a promising platform for QAHE. However, its inherent interlayer antiferromagnetic coupling hinders practical realization at high temperatures. In this study, we propose a novel approach to achieve interlayer ferromagnetic (FM) coupling in MBT bilayer by intercalating the septuple-layer of topological insulators XBi2Te4 (X=Ge, Sn, Pb). Using first-principles calculations, we demonstrate that the pz orbital of the X atom mediates interactions between interlayer Mn atoms, enabling FM coupling. Monte Carlo simulations predict a magnetic transition temperature of 38 K for the MnBi2Te4/PbBi2Te4/MnBi2Te4 heterostructure. Our band structure and topological analyses confirm the preservation of QAHE in all MnBi2Te4/XBi2Te4/MnBi2Te4 heterostructures, while the MnBi2Te4/PbBi2Te4/MnBi2Te4 heterostructure exhibits a topological band gap of 72 meV, significantly exceeding that of the pure MnBi2Te4 bilayer. Furthermore, a continuum model is developed to elucidate the underlying mechanism of the nontrivial topological states. Our work provides a practical pathway to achieving interlayer FM coupling in MnBi2Te4 bilayers, paving the way for high-temperature QAHE and advancing the development of magnetic topological insulators for quantum and spintronic applications.