Optical readout of the chemical potential of two-dimensional electrons
Optical readout of the chemical potential of two-dimensional electrons
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DOI：
10.1038/s41566-024-01377-3
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发表时间：
2023-04
期刊：
影响因子：
35
通讯作者：
Zhengchao Xia;Y. Zeng;B. Shen;Roei Dery;Kenji Watanabe;T. Taniguchi;J. Shan;K. Mak
中科院分区：
文献类型：
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作者：
Zhengchao Xia;Y. Zeng;B. Shen;Roei Dery;Kenji Watanabe;T. Taniguchi;J. Shan;K. Mak
电子系统的化学势（μ）是固体的基本性质。μ的精确测量对于理解电子相互作用和物质的量子态起着至关重要的作用。然而，由于小的样品体积和大的背景信号，在微米和纳米级样品中的热力学测量是具有挑战性的。本文报道了一种任意二维材料μ的光学读出技术。单层半导体传感器电容耦合到样品。传感器的光学响应决定了将其化学势固定在带边的偏置，并直接读取样品的μ值。我们展示了AB堆叠MoTe 2/WSe 2 moiré双层的技术。在直流灵敏度约为20 µeV Hz-1/2的条件下，得到了μ值，在交流灵敏度约为20 µ eV Hz-1/2的条件下，得到了层间电极化和压缩性。读数。结果表明，在掺杂密度为每摩尔单元一个空穴时，随着面外电场的增加，材料呈现出从Mott绝缘体到电荷转移绝缘体的相关绝缘状态。此外，我们对μ进行成像并量化样本的空间不均匀性。我们的工作为高空间分辨率和高时间分辨率测量二维量子材料的热力学性质打开了大门。
The chemical potential (μ) of an electron system is a fundamental property of a solid. A precise measurement ofμplays a crucial role in understanding the electron interaction and quantum states of matter. However, thermodynamics measurements in micro- and nanoscale samples are challenging because of the small sample volume and large background signals. Here we report an optical readout technique forμof an arbitrary two-dimensional material. A monolayer semiconductor sensor is capacitively coupled to the sample. The sensor optical response determines a bias that fixes its chemical potential to the band edge and directly reads theμvalue of the sample. We demonstrate the technique in AB-stacked MoTe2/WSe2moiré bilayers. We obtain theμvalue with a d.c. sensitivity of about 20 µeV Hz–1/2and the compressibility and interlayer electric polarization using a.c. readout. The results reveal a correlated insulating state at a doping density of one hole per moiré unit cell, which evolves from a Mott insulator to a charge-transfer insulator with an increasing out-of-plane electric field. Furthermore, we imageμand quantify the spatial inhomogeneity of the sample. Our work opens the door for high-spatial-resolution and high-temporal-resolution measurements of the thermodynamic properties of two-dimensional quantum materials.