Inducing itinerant ferromagnetism by manipulating van Hove singularity in epitaxial monolayer 1T-VSe2

Junyu Zong; Zhao-Yang Dong; Junwei Huang; Kaili Wang; Qi-Wei Wang; Qinghao Meng; Qichao Tian; Xiaodong Qiu; Yuyang Mu; Li Wang; Wei Ren; Xuedong Xie; Wang Chen; Yongheng Zhang; Can Wang; Fang-Sen Li; Shao-Chun Li; Jian-Xin Li; Hongtao Yuan; Yi Zhang

doi:10.1016/j.scib.2023.04.016

Inducing itinerant ferromagnetism by manipulating van Hove singularity in epitaxial monolayer 1T-VSe₂

Sci Bull (Beijing). 2023 May 30;68(10):990-997. doi: 10.1016/j.scib.2023.04.016. Epub 2023 Apr 13.

Authors

Junyu Zong¹, Zhao-Yang Dong², Junwei Huang³, Kaili Wang¹, Qi-Wei Wang¹, Qinghao Meng¹, Qichao Tian¹, Xiaodong Qiu¹, Yuyang Mu¹, Li Wang⁴, Wei Ren⁴, Xuedong Xie¹, Wang Chen¹, Yongheng Zhang¹, Can Wang⁵, Fang-Sen Li⁴, Shao-Chun Li⁵, Jian-Xin Li⁶, Hongtao Yuan⁷, Yi Zhang⁸

Affiliations

¹ National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China.
² Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094, China.
³ College of Engineering and Applied Sciences and National Laboratory of Solid-State Microstructures, Nanjing University, Nanjing 210093, China.
⁴ Vacuum Interconnected NanoTech Workstation (Nano-X), Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences, Suzhou 215123, China.
⁵ National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China; Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.
⁶ National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China; Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China. Electronic address: jxli@nju.edu.cn.
⁷ College of Engineering and Applied Sciences and National Laboratory of Solid-State Microstructures, Nanjing University, Nanjing 210093, China; Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China. Electronic address: htyuan@nju.edu.cn.
⁸ National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China; Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China. Electronic address: zhangyi@nju.edu.cn.

PMID: 37100643
DOI: 10.1016/j.scib.2023.04.016

Abstract

The itinerant ferromagnetism can be induced by a van Hove singularity (VHS) with a divergent density of states at Fermi level. Utilizing the giant magnified dielectric constant ε_r of SrTiO₃(111) substrate with cooling, here we successfully manipulated the VHS in the epitaxial monolayer (ML) 1T-VSe₂ film approaching to Fermi level via the large interfacial charge transfer, and thus induced a two-dimensional (2D) itinerant ferromagnetic state below 3.3 K. Combining the direct characterization of the VHS structure via angle-resolved photoemission spectroscopy (ARPES), together with the theoretical analysis, we ascribe the manipulation of VHS to the physical origin of the itinerant ferromagnetic state in ML 1T-VSe₂. Therefore, we further demonstrated that the ferromagnetic state in the 2D system can be controlled through manipulating the VHS by engineering the film thickness or replacing the substrate. Our findings clearly evidence that the VHS can serve as an effective manipulating degree of freedom for the itinerant ferromagnetic state, expanding the application potentials of 2D magnets for the next-generation information technology.

Keywords: 2D itinerant ferromagnetism; Angle-resolved photoemission spectroscopy; Electronic transport; Molecular beam epitaxy; Monolayer 1T-VSe(2); Van Hove singularity.