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Open Access Publications from the University of California

Evidence of Spin Frustration in a Vanadium Diselenide Monolayer Magnet.

  • Author(s): Wong, Ping Kwan Johnny
  • Zhang, Wen
  • Bussolotti, Fabio
  • Yin, Xinmao
  • Herng, Tun Seng
  • Zhang, Lei
  • Huang, Yu Li
  • Vinai, Giovanni
  • Krishnamurthi, Sridevi
  • Bukhvalov, Danil W
  • Zheng, Yu Jie
  • Chua, Rebekah
  • N'Diaye, Alpha T
  • Morton, Simon A
  • Yang, Chao-Yao
  • Ou Yang, Kui-Hon
  • Torelli, Piero
  • Chen, Wei
  • Goh, Kuan Eng Johnson
  • Ding, Jun
  • Lin, Minn-Tsong
  • Brocks, Geert
  • de Jong, Michel P
  • Castro Neto, Antonio H
  • Wee, Andrew Thye Shen
  • et al.

Monolayer VSe2 , featuring both charge density wave and magnetism phenomena, represents a unique van der Waals magnet in the family of metallic 2D transition-metal dichalcogenides (2D-TMDs). Herein, by means of in situ microscopy and spectroscopic techniques, including scanning tunneling microscopy/spectroscopy, synchrotron X-ray and angle-resolved photoemission, and X-ray absorption, direct spectroscopic signatures are established, that identify the metallic 1T-phase and vanadium 3d1 electronic configuration in monolayer VSe2 grown on graphite by molecular-beam epitaxy. Element-specific X-ray magnetic circular dichroism, complemented with magnetic susceptibility measurements, further reveals monolayer VSe2 as a frustrated magnet, with its spins exhibiting subtle correlations, albeit in the absence of a long-range magnetic order down to 2 K and up to a 7 T magnetic field. This observation is attributed to the relative stability of the ferromagnetic and antiferromagnetic ground states, arising from its atomic-scale structural features, such as rotational disorders and edges. The results of this study extend the current understanding of metallic 2D-TMDs in the search for exotic low-dimensional quantum phenomena, and stimulate further theoretical and experimental studies on van der Waals monolayer magnets.

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