论文标题
在分子束外延增长的Mnbi2te4薄膜中量化的异常大厅电阻率
Quantized anomalous Hall resistivity achieved in molecular beam epitaxy-grown MnBi2Te4 thin films
论文作者
论文摘要
固有的磁性绝缘体MNBI2TE4为高温量子异常大厅（QAH）效应以及各种新型拓扑量子阶段提供了可行的途径。尽管在去角质的MNBI2TE4薄片中观察到了量化的传输特性，但要实现分子束外延（MBE）种植的MNBI2TE4薄膜甚至接近量化状态仍然是一个巨大的挑战。在这项工作中，我们报告了MBE生长的MNBI2TE4薄膜中量化异常的大厅电阻率的实现，其化学势通过受控的原位氧气暴露和最高门控。我们发现，伸长后的解散显然会升高温度以实现大厅电阻率的量化，同时也增加了残留的纵向电阻率，这表明高质量的QAH Puddles的图像与隧道障碍物弱耦合。这些结果有助于阐明先前对MNBI2TE4的实验研究的难题，并找到摆脱获得量化运输特性的MNBI2TE4样品的大难度。
The intrinsic magnetic topological insulator MnBi2Te4 provides a feasible pathway to high temperature quantum anomalous Hall (QAH) effect as well as various novel topological quantum phases. Although quantized transport properties have been observed in exfoliated MnBi2Te4 thin flakes, it remains a big challenge to achieve molecular beam epitaxy (MBE)-grown MnBi2Te4 thin films even close to the quantized regime. In this work, we report the realization of quantized anomalous Hall resistivity in MBE-grown MnBi2Te4 thin films with the chemical potential tuned by both controlled in-situ oxygen exposure and top gating. We find that elongated post-annealing obviously elevates the temperature to achieve quantization of the Hall resistivity, but also increases the residual longitudinal resistivity, indicating a picture of high-quality QAH puddles weakly coupled by tunnel barriers. These results help to clarify the puzzles in previous experimental studies on MnBi2Te4 and to find a way out of the big difficulty in obtaining MnBi2Te4 samples showing quantized transport properties.
