Dimensional crossover and symmetry transformation of the charge density waves in VSe2

P. Chen; Y. -H. Chan; R. -Y. Liu; H. T. Zhang; Q. Gao; A. -V. Fedorov; M. Y. Chou; T. -C. Chiang

doi:10.1103/physrevb.105.l161404

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arXiv · 2302.10031

Dimensional crossover and symmetry transformation of the charge density waves in VSe2

P. Chen·Y. -H. Chan·R. -Y. Liu·H. T. Zhang·Q. Gao·A. -V. Fedorov·M. Y. Chou·T. -C. Chiang

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Abstract

Collective phenomena in solids can be sensitive to the dimensionality of the system; a case of special interest is VSe2, which shows a (r7 x r3) charge density wave (CDW) in the single layer with the three-fold symmetry in the normal phase spontaneously broken, in contrast to the (4 x 4) in-plane CDW in the bulk. Angle-resolved photoemission spectroscopy (ARPES) from VSe2 ranging from a single layer to the bulk reveals the evolution of the electronic structure including the Fermi surface contours and the CDW gap. At a thickness of two layers, the ARPES maps are already nearly bulklike, but the transition temperature TC for the (4 x 4) CDW is much higher than the bulk value of 110 K. These results can be understood as a result of dimensional crossover of phonon instability driven by a competition of nesting vectors. Our study provides key insights into the CDW mechanisms and offers a perspective in the search and control of emergent phases in quantum materials.

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P. Chen, Y. -H. Chan, R. -Y. Liu, H. T. Zhang, Q. Gao, A. -V. Fedorov, M. Y. Chou, T. -C. Chiang. 2023-02-20. Dimensional crossover and symmetry transformation of the charge density waves in VSe2. https://doi.org/10.1103/physrevb.105.l161404

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