近日，美国康奈尔大学的Jie Shan及其研究小组取得一项新进展。经过不懈努力，他们发现了MoTe₂中分数陈绝缘体的热力学证据。相关研究成果已于2023年7月26日在国际权威学术期刊《自然》上发表。

该研究团队通过结合局部电子压缩率和磁光测量，报道了零磁场下小角扭曲双层MoTe₂中整数和分数陈绝缘体的热力学证据。当空穴填充因子ν 分别为1和2/3时，系统不可压缩并自发破缺时间反演对称性。从填充因子中状态随外加磁场的色散可以看出它们分别是整数和分数陈绝缘体。研究人员进一步证明，电场调谐拓扑相变与陈绝缘体密切相关。这一研究发现为量子分数霍尔电导和任意子激发和编织在半导体纳米材料中的演示铺平了道路。

据悉，陈绝缘体是量子霍尔态的晶格类似物，可以在零磁场下表现出高温拓扑序，从而用于制造下一代拓扑量子器件。到目前为止，整数陈绝缘体已经在几个零磁场系统中被实验证实，但分数陈绝缘体仅在有限磁场下的石墨烯基系统中被报道。随着可调谐拓扑平带的半导体莫尔材料的出现，实现分数陈绝缘体已成为可能，为这一领域开辟了新的机会。

附：英文原文

Title: Thermodynamic evidence of fractional Chern insulator in moiré MoTe₂

Author: Zeng, Yihang, Xia, Zhengchao, Kang, Kaifei, Zhu, Jiacheng, Knppel, Patrick, Vaswani, Chirag, Watanabe, Kenji, Taniguchi, Takashi, Mak, Kin Fai, Shan, Jie

Issue&Volume: 2023-07-26

Abstract: Chern insulators, which are the lattice analogs of the quantum Hall states, can potentially manifest high-temperature topological orders at zero magnetic field to enable next-generation topological quantum devices. To date, integer Chern insulators have been experimentally demonstrated in several systems at zero magnetic field, but fractional Chern insulators have been reported only in graphene-based systems under a finite magnetic field. The emergence of semiconductor moiré materials, which support tunable topological flat bands, opens a new opportunity to realize fractional Chern insulators. Here, we report thermodynamic evidence of both integer and fractional Chern insulators at zero magnetic field in small-angle twisted bilayer MoTe₂ by combining the local electronic compressibility and magneto-optical measurements. At hole filling factor ν = 1 and 2/3, the system is incompressible and spontaneously breaks time reversal symmetry. We show that they are integer and fractional Chern insulators, respectively, from the dispersion of the state in filling factor with applied magnetic field. We further demonstrate electric-field-tuned topological phase transitions involving the Chern insulators. Our findings pave the way for demonstration of quantized fractional Hall conductance and anyonic excitation and braiding in semiconductor moiré materials.

DOI: 10.1038/s41586-023-06452-3

Source: https://www.nature.com/articles/s41586-023-06452-3