Zhang Gaojie, Wu Hao, Zhang Liang, Zhang Shanfei, Yang Li, Gao Pengfei, Wen Xiaokun, Jin Wen, Guo Fei, Xie Yuanmiao, Li Hongda, Tao Boran, Zhang Wenfeng, Chang Haixin
Center for Joining and Electronic Packaging, State Key Laboratory of Material Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China.
Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China.
Adv Sci (Weinh). 2022 Jan;9(1):e2103173. doi: 10.1002/advs.202103173. Epub 2021 Oct 27.
The combination of semiconductivity and tunable ferromagnetism is pivotal for electrical control of ferromagnetism and next-generation low-power spintronic devices. However, Curie temperatures (T ) for most traditional intrinsic ferromagnetic semiconductors (≤200 K) and recently discovered two-dimensional (2D) ones (<70 K) are far below room temperature. 2D van der Waals (vdW) semiconductors with intrinsic room-temperature ferromagnetism remain elusive considering the unfavored 2D long-range ferromagnetic order indicated by Mermin-Wagner theorem. Here, vdW semiconductor Cr Ga Te crystals exhibiting highly tunable above-room-temperature ferromagnetism with bandgap 1.62-1.66 eV are reported. The saturation magnetic moment (M ) of Cr Ga Te crystals can be effectively regulated up to ≈5.4 times by tuning Cr content and ≈75.9 times by changing the thickness. vdW Cr Ga Te ultrathin semiconductor crystals show robust room-temperature ferromagnetism with the 2D quantum confinement effect, enabling T 314.9-329 K for nanosheets, record-high for intrinsic vdW 2D ferromagnetic semiconductors. This work opens an avenue to room-temperature 2D vdW ferromagnetic semiconductor for 2D electronic and spintronic devices.
半导体特性与可调谐铁磁性的结合对于铁磁性的电控制和下一代低功耗自旋电子器件至关重要。然而，大多数传统本征铁磁半导体的居里温度（(T)）（≤200 K）以及最近发现的二维（2D）铁磁半导体的居里温度（<70 K）都远低于室温。考虑到Mermin-Wagner定理所表明的二维长程铁磁序不受青睐，具有本征室温铁磁性的二维范德华（vdW）半导体仍然难以捉摸。在此，报道了具有1.62 - 1.66 eV带隙、表现出高度可调的室温以上铁磁性的vdW半导体CrGaTe晶体。通过调整Cr含量，CrGaTe晶体的饱和磁矩（(M)）可有效调节至约5.4倍，通过改变厚度可调节至约75.9倍。vdW CrGaTe超薄半导体晶体在二维量子限制效应下表现出稳健的室温铁磁性，纳米片的居里温度(T)为314.9 - 329 K，这是本征vdW二维铁磁半导体的创纪录高温。这项工作为用于二维电子和自旋电子器件的室温二维vdW铁磁半导体开辟了一条途径。
