Tuning 2D magnetism in Fe3+XGeTe2 films by element doping

Shanshan Liu; Zihan Li; Ke Yang; Enze Zhang; Awadhesh Narayan; Xiaoqian Zhang; Jiayi Zhu; Wenqing Liu; Zhiming Liao; Masaki Kudo; Takaaki Toriyama; Yunkun Yang; Qiang Li; Linfeng Ai; Ce Huang; Jiabao Sun; Xiaojiao Guo; Wenzhong Bao; Qingsong Deng; Yanhui Chen; Lifeng Yin; Jian Shen; Xiaodong Han; Syo Matsumura; Jin Zou; Yongbing Xu; Xiaodong Xu; Hua Wu; Faxian Xiu

doi:10.1093/nsr/nwab117

Tuning 2D magnetism in Fe_3+XGeTe₂ films by element doping

Natl Sci Rev. 2021 Jul 2;9(6):nwab117. doi: 10.1093/nsr/nwab117. eCollection 2022 Jun.

Authors

Shanshan Liu¹, Zihan Li¹, Ke Yang², Enze Zhang¹, Awadhesh Narayan³, Xiaoqian Zhang⁴, Jiayi Zhu⁵, Wenqing Liu⁶, Zhiming Liao⁷, Masaki Kudo⁸, Takaaki Toriyama⁸, Yunkun Yang¹, Qiang Li¹, Linfeng Ai¹, Ce Huang¹, Jiabao Sun⁶, Xiaojiao Guo⁹, Wenzhong Bao⁹, Qingsong Deng¹⁰, Yanhui Chen¹⁰, Lifeng Yin¹, Jian Shen¹, Xiaodong Han¹⁰, Syo Matsumura⁸, Jin Zou⁷, Yongbing Xu⁴, Xiaodong Xu⁵, Hua Wu¹, Faxian Xiu¹

Affiliations

¹ State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China.
² College of Science, University of Shanghai for Science and Technology, Shanghai 200093, China.
³ Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India.
⁴ School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China.
⁵ Department of Physics, University of Washington, Seattle, WA 98195-1560, USA.
⁶ Department of Electronic Engineering, Royal Holloway University of London, Egham TW20 0EX, UK.
⁷ Materials Engineering, The University of Queensland, Brisbane QLD 4072, Australia.
⁸ The Ultramicroscopy Research Center, Kyushu University, Fukuoka 819-0395, Japan.
⁹ State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai 200433, China.
¹⁰ Beijing Key Laboratory of Microstructure and Property of Advanced Materials, Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100124, China.

Abstract

Two-dimensional (2D) ferromagnetic materials have been discovered with tunable magnetism and orbital-driven nodal-line features. Controlling the 2D magnetism in exfoliated nanoflakes via electric/magnetic fields enables a boosted Curie temperature (T _C) or phase transitions. One of the challenges, however, is the realization of high T _C 2D magnets that are tunable, robust and suitable for large scale fabrication. Here, we report molecular-beam epitaxy growth of wafer-scale Fe_3+XGeTe₂ films with T _C above room temperature. By controlling the Fe composition in Fe_3+XGeTe₂, a continuously modulated T _C in a broad range of 185-320 K has been achieved. This widely tunable T _C is attributed to the doped interlayer Fe that provides a 40% enhancement around the optimal composition X = 2. We further fabricated magnetic tunneling junction device arrays that exhibit clear tunneling signals. Our results show an effective and reliable approach, i.e. element doping, to producing robust and tunable ferromagnetism beyond room temperature in a large-scale 2D Fe_3+XGeTe₂ fashion.

Keywords: 2D ferromagnetic material; Fe3+XGeTe2 film; TC tunability; above room temperature; element doping.