Schüler Michael, De Giovannini Umberto, Hübener Hannes, Rubio Angel, Sentef Michael A, Werner Philipp
Stanford Institute for Materials and Energy Sciences (SIMES), SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA.
Department of Physics, University of Fribourg, 1700 Fribourg, Switzerland.
Sci Adv. 2020 Feb 28;6(9):eaay2730. doi: 10.1126/sciadv.aay2730. eCollection 2020 Feb.
Topologically nontrivial two-dimensional materials hold great promise for next-generation optoelectronic applications. However, measuring the Hall or spin-Hall response is often a challenge and practically limited to the ground state. An experimental technique for tracing the topological character in a differential fashion would provide useful insights. In this work, we show that circular dichroism angle-resolved photoelectron spectroscopy provides a powerful tool that can resolve the topological and quantum-geometrical character in momentum space. In particular, we investigate how to map out the signatures of the momentum-resolved Berry curvature in two-dimensional materials by exploiting its intimate connection to the orbital polarization. A spin-resolved detection of the photoelectrons allows one to extend the approach to spin-Chern insulators. The present proposal can be extended to address topological properties in materials out of equilibrium in a time-resolved fashion.
拓扑非平凡二维材料在下一代光电子应用中极具潜力。然而，测量霍尔或自旋霍尔响应通常是一项挑战，并且实际上仅限于基态。一种以差分方式追踪拓扑特性的实验技术将提供有用的见解。在这项工作中，我们表明圆二色角分辨光电子能谱提供了一个强大的工具，能够解析动量空间中的拓扑和量子几何特性。特别是，我们通过利用其与轨道极化的紧密联系，研究如何绘制二维材料中动量分辨贝里曲率的特征。对光电子的自旋分辨检测使人们能够将该方法扩展到自旋陈绝缘体。本提议可以扩展到以时间分辨方式研究非平衡态材料的拓扑性质。
