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Free keywords:
Calculations, Charge density, Charge density waves, Phase separation, Superconducting materials, Transition metals, Ab initio calculations, Charge modulation, Metallic transition, Single layer, Strain induced, Stripe phasis, Structural instability, Structural modulations, Modulation
Abstract:
Charge density waves are ubiquitous phenomena in metallic transition metal dichalcogenides. In NbSe2, a triangular 3 × 3 structural modulation is coupled to a charge modulation. Recent experiments reported evidence for a triangular-stripe transition at the surface, due to strain or accidental doping and associated to a 4 × 4 modulation. We employ ab initio calculations to investigate the strain-induced structural instabilities in a pristine single layer and analyse the energy hierarchy of the structural and charge modulations. Our results support the observation of phase separation between triangular and stripe phases in 1H-NbSe2, relating the stripe phase to compressive isotropic strain, favouring the 4 × 4 modulation. The observed wavelength of the charge modulation is also reproduced with a good accuracy. © 2020, The Author(s).
