CNR ExploRA

Articolo in rivista, 2019, ENG, 10.1002/adma.201901185

Evidence of Spin Frustration in a Vanadium Diselenide Monolayer Magnet

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; Yang, Kui-Hon Ou; Torelli, Piero; Chen, Wei; Goh, Kuan Eng Johnson; Ding, Jun; Lin, Minn-Tsong; Brocks, Geert; de Jong, Michel P.; Neto, Antonio H. Castro; Wee, Andrew Thye Shen

Natl Univ Singapore; Natl Univ Singapore; Natl Univ Singapore; ASTAR; Natl Univ Singapore; CNR; Univ Twente; Univ Twente; Nanjing Forestry Univ; Ural Fed Univ; Lawrence Berkeley Natl Lab; Natl Taiwan Univ; Natl Univ Singapore; Univ Twente

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 3d(1) 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.

Advanced materials (Weinh., Print) 31 (23)