Measurement of electronic structure in van der Waals ferromagnet Fe5–xGeTe2

Measurement of electronic structure in van der Waals ferromagnet Fe5–xGeTe2

by | Mar 10, 2022 | 2022, 本组论文

Chinese Physics B 31(5), 057404 (2022)

Kui Huang (黄逵), Zhenxian Li (李政贤), Deping Guo (郭的坪), Haifeng Yang (杨海峰), Yiwei Li (李一苇), Aiji Liang (梁爱基), Fan Wu (吴凡), Lixuan Xu (徐丽璇), Lexian Yang (杨乐仙), Wei Ji (季威), Yanfeng Guo (郭艳峰), Yulin Chen (陈宇林)* and Zhongkai Liu (柳仲楷)*

Abstract

As a van der Waals ferromagnet with high Curie temperature, Fe5–xGeTe2 has attracted tremendous interests recently. Here, using high-resolution angle-resolved photoemission spectroscopy (ARPES), we systematically investigated the electronic structure of Fe5–xGeTe2 crystals and its temperature evolution. Our ARPES measurement reveals two types of band structures from two different terminations with slight kz evolution. Interestingly, across the ferromagnetic transition, we observed the merging of two split bands above the Curie temperature, suggesting the band splitting due to the exchange interaction within the itinerant Stoner model. Our results provide important insights into the electronic and magnetic properties of Fe5–xGeTe2 and the understanding of magnetism in a two-dimensional ferromagnetic system.

DOI:10.1088/1674-1056/ac5c3c

Light helicity detector based on 2D magnetic semiconductor CrI3

Light helicity detector based on 2D magnetic semiconductor CrI3

by | Nov 25, 2021 | 2021, 本组论文

Nature Communications 12: 6874 (2021)

Xing Cheng, Zhixuan Cheng, Cong Wang, Minglai Li, Pingfan Gu, Shiqi Yang, Yanping Li, Kenji Watanabe, Takashi Taniguchi, Wei Ji & Lun Dai

Two-dimensional magnetic semiconductors provide a platform for studying physical phenomena at atomically thin limit, and promise magneto-optoelectronic devices application. Here, we report light helicity detectors based on graphene-CrI3-graphene vdW heterostructures. We investigate the circularly polarized light excited current and reflective magnetic circular dichroism (RMCD) under various magnetic fields in both monolayer and multilayer CrI3 devices. The devices exhibit clear helicity-selective photoresponse behavior determined by the magnetic state of CrI3. We also find abnormal negative photocurrents at higher bias in both monolayer and multilayer CrI3. A possible explanation is proposed for this phenomenon. Our work reveals the interplay between magnetic and optoelectronic properties in CrI3 and paves the way to developing spin-optoelectronic devices.