Metallic 1T Phase, 3d<sup>1</sup> Electronic Configuration and Charge Density Wave Order in Molecular Beam Epitaxy Grown Monolayer Vanadium Ditelluride

Wong, Ping Kwan Johnny; Zhang, Wen; Zhou, Jun; Bussolotti, Fabio; Yin, Xinmao; Zhang, Lei; N’Diaye, Alpha T.; Morton, Simon A.; Chen, Wei; Goh, Kuan Eng Johnson; Jong, M. P. de; Feng, Yuan Ping; Wee, Andrew Thye Shen

doi:10.1021/acsnano.9b05349

Cited by 58 publications

(62 citation statements)

References 37 publications

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“…Room-temperature ferromagnetism has been observed in VTe2 nanoplates 2 . However, FM order was absent in monolayer VTe2 according to 3 / 18 recent experimental studies 36,37 . The interplay between the long-range charge and spin orders in monolayer VTe2 is yet unknown.Here we investigate the different CDW phases in monolayer VTe2 by STM/STS and DFT calculations.…”

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confidence: 86%

Multimorphism and gap opening of charge-density-wave phases in monolayer VTe2

Liu

et al. 2020

Nano Res.

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Vanadium dichalcogenides have attracted increasing interests for the charge density wave phenomena and possible ferromagnetism. Here, we report on the multiphase behavior and gap opening in monolayer VTe2 grown by molecular beam epitaxy. Scanning tunneling microscopy (STM) and spectroscopy study revealed the (4×4) metallic and gapped (2√3×2√3) charge-density wave (CDW) phases with an energy gap of ~40 meV. Through the in-plane condensation of vanadium atoms, the typical star-of-David clusters and truncated triangle-shaped clusters are formed in the (4×4) and (2√3×2√3) phases respectively, resulting in different surface morphologies and electronic structures as confirmed by density functional theory (DFT) calculations with on-site Coulomb repulsion. The CDW-driven reorganization of the atomic structure weakens the ferromagnetic superexchange coupling and strengthens the antiferromagnetic exchange coupling on the contrary, suppressing the long-range magnetic order in monolayer VTe2.The electron correlation is found to be important to explain the gap opening in the (2√3×2√3) phase. / 18Two-dimensional (2D) transition-metal dichalcogenides (TMDs) are recently attracting great attention for their diverse physical properties such as ferromagnetism 1,2 , Mott-insulator phase 3,4 , quantum Hall effect 5-7 , superconductivity and charge density wave (CDW) [8][9][10][11] . CDW is a periodic symmetry-lowering redistribution of charge in a material, accompanied with periodic modulation of the atomic lattice and electronic densities. The CDW transition in the group VB dichalcogenides, such as VS2, VSe2, NbSe2, TaS2, TaSe2 and TaTe2, has been extensively studied [12][13][14][15][16][17][18][19][20] . The phase transition exhibits a layer-dependent behavior, for instance, VSe2 and NbSe2 have increased CDW transition temperatures as the thicknesses reduce down to a few monolayers. In monolayer VSe2 and NbSe2, the TCDW can be enhanced to 140 K and 145 K compared to 110 K and 33 K of the bulk TCDW respectively [21][22][23][24] . The intricate interplay between CDW and other collective electronic states such as superconductivity has also been explored in NbSe2 and TaS2 25,26 . While the driving mechanisms of CDW in twodimensional TMDs consisting of Fermi surface nesting 27,28 , saddle point singularities 29,30 and electron-phonon coupling [31][32][33][34] have been proposed, a consistent picture on the CDW formation is still to emerge.As for VTe2, CDW phase transition has been observed in VTe2 thin films as the change of resistance at 240 K and 135 K, which can be driven by an electric field due to local Joule heating 35 . When the thickness reduces from multilayer to single layer, the absence of interlayer interaction result in the structural transition from a monoclinic distorted 1Tʹ structure to a hexagonal 1T structure 36 . The 1Tʹ structure has a (3×1) double zigzag chain-like modulation of V atoms, which arise from the in-plane metal coordination through d orbital hybridization. As the temperature is cooled below TCDW, the mo...

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confidence: 86%

Multimorphism and gap opening of charge-density-wave phases in monolayer VTe2

Liu

et al. 2020

Nano Res.

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“…97 G, XMCD hysteresis loops obtained at the Co and V L 3 edges, respectively, at 65 K, which demonstrate the ferromagnetic hysteresis loop of VSe 2 and the antiferromagnetic coupling between Co and V spins 100 to the monolayer. 105 Remarkably, traits of spin frustration have been discovered for the first time in the monolayer by systematic field-dependent magnetization and temperature-dependent susceptibility measurements ( Figure 5E), possibly due to its 2D triangular spin lattice on which three neighboring spins are unable to mutually antialigned with each other ( Figure 5F). This particular finding highlights an exciting example of the exotic quantum phases that can be hosted by 2D-vdW magnets.…”

Section: V-based Vdw Magnetsmentioning

confidence: 95%

Van der Waals magnets: Wonder building blocks for two‐dimensional spintronics?

Zhang

Wong

Zhu

et al. 2019

InfoMat

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105

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The unprecedented realization of two‐dimensional (2D) van der Waals magnets excitingly extends the synergy between spintronics and 2D materials, started with graphene over the last decade. This article reviews the recent milestones in the development of 2D magnets and its derived heterostructures. In particular, a number of critical challenges centered around the scalability, ambient stability and Curie temperature of these atomically thin magnets are discussed. This mini‐review also provides an outlook on what the future might hold for this integrated field of 2D spintronics, and assesses its potential in postsilicon electronics.

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“…It has also been suggested that the CDW transition opens an energy gap at the Fermi level that in turn suppresses the intrinsic ferromagnetic ordering 41,46–49 . Similarly, MBE‐grown VTe 2 MLs on graphite demonstrate a 4 × 4 CDW order at low temperature and XMCD measurements rule out the existence of intrinsic ferromagnetic order 50 …”

Section: Intrinsic Magnetism In 2d Tmcsmentioning

confidence: 96%

Two‐dimensional magnetic transition metal chalcogenides

2021

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The field of two‐dimensional (2D) magnets has expanded rapidly during the past several years since the first demonstration of intrinsic 2D magnetism in atomically thin CrI3 and Cr2Ge2Te6 in 2017. 2D transition metal chalcogenides (TMCs), a class of strongly correlated materials, have exhibited a wide variety of novel electronic and optical properties, and more recently magnetism. Here, we review recent experimental progress achieved in the growth of 2D magnetic TMC materials using chemical vapor deposition and molecular beam epitaxy methods. Outstanding examples include the demonstration of room temperature intrinsic and extrinsic ferromagnetism in monolayer VSe2, MnSe2, Cr3Te4, V‐doped WSe2, and so on. A brief discussion on the origin of the exotic magnetic properties and emergent phenomena is also presented. Finally, we summarize the remaining challenges and future perspective on the development of 2D magnetic materials for next‐generation spintronic devices.

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Metallic 1T Phase, 3d¹ Electronic Configuration and Charge Density Wave Order in Molecular Beam Epitaxy Grown Monolayer Vanadium Ditelluride

Cited by 58 publications

References 37 publications

Multimorphism and gap opening of charge-density-wave phases in monolayer VTe2

Multimorphism and gap opening of charge-density-wave phases in monolayer VTe2

Van der Waals magnets: Wonder building blocks for two‐dimensional spintronics?

Two‐dimensional magnetic transition metal chalcogenides

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Metallic 1T Phase, 3d1 Electronic Configuration and Charge Density Wave Order in Molecular Beam Epitaxy Grown Monolayer Vanadium Ditelluride

Cited by 58 publications

References 37 publications

Multimorphism and gap opening of charge-density-wave phases in monolayer VTe2

Multimorphism and gap opening of charge-density-wave phases in monolayer VTe2

Van der Waals magnets: Wonder building blocks for two‐dimensional spintronics?

Two‐dimensional magnetic transition metal chalcogenides

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Metallic 1T Phase, 3d¹ Electronic Configuration and Charge Density Wave Order in Molecular Beam Epitaxy Grown Monolayer Vanadium Ditelluride