标题： 电荷中性磁性拓扑绝缘体Sb掺杂MnBi6Te10中原子内单元电荷重排的光谱证据 显示英文标题

标题： Spectroscopic evidence of intra-unit-cell charge redistribution in charge-neutral magnetic topological insulator Sb-doped MnBi6Te10

摘要： 磁性拓扑绝缘体MnBi$_{6}$Te$_{10}$由于能够通过精确控制反位缺陷来保持铁磁性，已成为实现量子异常霍尔效应（QAHE）的有前景候选材料。实现QAHE的下一个重要任务是调整化学势进入由破缺时间反演对称性形成的能隙。这里我们揭示了即使总体掺杂表明接近电荷中性的条件下，仍存在晶胞内的电荷重新分布。 通过在最优的18% Sb掺杂MnBi$_{6}$Te$_{10}$上进行时间分辨和角度分辨光电子能谱（trARPES）测量，我们观察到MnBi$_{2}$Te$_{4}$和单Bi$_{2}$Te$_{3}$终止层上的瞬态表面光电压（SPV）效应。此外，我们观察到能带结构随时间的变化分裂，表明存在多个具有不同幅度的SPV偏移。这一观察结果表明，名义上具有相同终止层的相邻平台表现出强烈的单元内电荷重新分布，从而导致自发的电极化。这与静态微ARPES测量结果一致，显示出显著偏离电荷中性构型的掺杂变化。我们的发现强调了通过化学掺杂来设计Mn-Bi-Te材料家族以实现量子反常霍尔效应的挑战。实现所需的拓扑量子相需要均匀的载流子掺杂和铁磁基态。 此外，铁磁性 Mn(Bi$_{0.82}$Sb$_{0.18}$)$_{6}$Te$_{10}$每个晶胞内的光致极化可能为光电子学和自旋电子学开辟新的可能性。 显示英文摘要

摘要： The magnetic topological insulator MnBi$_{6}$Te$_{10}$ has emerged as a promising candidate for realizing the quantum anomalous Hall effect (QAHE), owing to its ability to retain ferromagnetism through precise control of anti-site defects. The next important task for realizing the QAHE is to tune the chemical potential into the energy gap formed by the broken time-reversal symmetry. Here we reveal an intra-unit-cell charge redistribution even when the overall doping suggests a near-charge-neutral condition. By performing time- and angle-resolved photoemission spectroscopy (trARPES) on the optimally 18% Sb-doped MnBi$_{6}$Te$_{10}$, we observe transient surface photovoltage (SPV) effects on both the MnBi$_{2}$Te$_{4}$ and single-Bi$_{2}$Te$_{3}$ terminations. Furthermore, we observe a time-dependent splitting of the band structure indicating multiple SPV shifts with different magnitudes. This observation suggests that adjacent plateaus with nominally the same terminating layer exhibit a strong intra-unit-cell charge redistribution, resulting in spontaneous electrical polarization. This is consistent with static micro-ARPES measurements revealing significant doping deviations from the charge-neutral configuration. Our findings underscore the challenges of engineering the family of Mn-Bi-Te materials to realize QAHE purely through chemical doping. Achieving the desired topological quantum phase requires both a uniform carrier doping and a ferromagnetic ground state. Furthermore, the light-induced polarization within each unit cell of ferromagnetic Mn(Bi$_{0.82}$Sb$_{0.18}$)$_{6}$Te$_{10}$ may open new possibilities for optoelectronic and spintronics.