磁性拓扑绝缘体双层中的栅极可调巨反常霍尔效应
Gate-tunable giant anomalous Hall effect in magnetic topological insulator bilayer
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中文总结 AI 辅助
研究利用计算和模拟，探讨磁性拓扑绝缘体双层中量子态及演化。通过静电门控和表面化学功能化实现拓扑到传统反常霍尔 regime的转变，增强面内交换作用，提高磁有序温度，为可重构量子器件发展提供框架。
中文摘要 AI 辅助
在二维极限下，本征磁性拓扑绝缘体MnBi2Te4为探索厚度依赖的量子态及其在外部扰动下的演化提供了一个引人注目的平台。利用第一性原理计算和经典海森堡蒙特卡罗模拟，证明了静电门控和表面化学功能化可以驱动从拓扑到传统反常霍尔 regime的系统转变。此转变由费米能级从拓扑间隙的同时移动和层间耦合从反铁磁到铁磁序的反转控制。结果表明，空穴掺杂将费米能级驱动到价带，由于贝里曲率热点产生了高达1127 S/cm的异常高反常霍尔电导率。相比之下，表面化学掺杂驱动一种拓扑状态，其中本征σxy通过二维薄膜的手性边缘模式与金属体态的光谱共存从e2/h降低到~0.86 e2/h。此外，表明两种调谐途径都显著增强了面内交换相互作用，导致相对于原始双层的磁有序温度大幅增加。这些结果为在超薄MnBi2Te4中同时设计拓扑、磁性和输运性质建立了一个通用框架，对可重构量子器件的发展具有直接意义。
英文摘要
In the two-dimensional limit, the intrinsic magnetic topological insulator MnBi2Te4 provides a compelling platform for exploring thickness-dependent quantum states and their evolution under external perturbations. Using first-principles calculations and classical Heisenberg Monte Carlo simulations, we demonstrate that electrostatic gating and surface chemical functionalization can drive a systematic crossover from the topological to the conventional anomalous Hall regime. This transition is governed by the simultaneous shift of the Fermi level away from the topological gap and a reversal of interlayer coupling from antiferromagnetic to ferromagnetic order. Results reveal that hole doping drives the Fermi level into the valence bands, inducing an exceptionally high anomalous Hall conductivity of 1127 S/cm arising from Berry curvature hot spots. In contrast, surface chemical doping drives a topological state where intrinsic $σ_{xy}$ is reduced from $e^2/h$ to $\sim 0.86\ e^2/h$ by the spectral coexistance of chiral edge mode with metallic bulk states of the two-dimensional film. Furthermore, we show that both tuning routes significantly enhance in-plane exchange interactions, leading to a substantial increase in the magnetic ordering temperature relative to the pristine bilayer. These results establish a versatile framework for the simultaneous engineering of topological, magnetic, and transport properties in ultrathin MnBi2Te4, offering direct implications for the development of reconfigurable quantum devices.
