Evidence of Spin Frustration in a Vanadium Diselenide Monolayer Magnet

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

doi:10.1002/adma.201901185

Evidence of Spin Frustration in a Vanadium Diselenide Monolayer Magnet

Adv Mater. 2019 Jun;31(23):e1901185. doi: 10.1002/adma.201901185. Epub 2019 Apr 18.

Authors

Ping Kwan Johnny Wong¹, Wen Zhang², Fabio Bussolotti³, Xinmao Yin², Tun Seng Herng⁴, Lei Zhang^{1

2}, Yu Li Huang², Giovanni Vinai⁵, Sridevi Krishnamurthi⁶, Danil W Bukhvalov^{7

8}, Yu Jie Zheng², Rebekah Chua², Alpha T N'Diaye⁹, Simon A Morton⁹, Chao-Yao Yang¹⁰, Kui-Hon Ou Yang¹⁰, Piero Torelli⁵, Wei Chen^{1

2

11}, Kuan Eng Johnson Goh^{2

3}, Jun Ding⁴, Minn-Tsong Lin¹⁰, Geert Brocks⁶, Michel P de Jong¹², Antonio H Castro Neto^{1

2}, Andrew Thye Shen Wee^{1

2}

Affiliations

¹ Centre for Advanced 2D Materials (CA2DM) and Graphene Research Centre (GRC), National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore.
² Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore.
³ Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*Star), 2 Fusionopolis Way, Innovis, Singapore, 138634, Singapore.
⁴ Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117575, Singapore.
⁵ Instituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park, S.S. Km 163.5, Trieste, I-34149, Italy.
⁶ Computational Materials Science, Faculty of Science and Technology and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500, AE, Enschede, The Netherlands.
⁷ College of Science, Institute of Materials Physics and Chemistry, Nanjing Forestry University, Nanjing, 210037, P. R. China.
⁸ Institute of Physics and Technology, Ural Federal University, Mira Street 19, 620002, Yekaterinburg, Russia.
⁹ Advanced Light Source (ALS), Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
¹⁰ Department of Physics, National Taiwan University, Taipei, 10617, Taiwan.
¹¹ Department of Chemistry, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore.
¹² NanoElectronics Group, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500, AE, Enschede, The Netherlands.

PMID: 30997712
DOI: 10.1002/adma.201901185

Abstract

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.

Keywords: 2D materials; monolayer magnet; spin frustration; van der Waals epitaxy; vanadium diselenide.

Abstract

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