20-021 Strain-induced stripe phase in charge-ordered single layer NbSe_2
최종 수정일: 2020년 5월 14일
Fabrizio Cossu, Krisztián Palotás, Sagar Sarkar, Igor Di Marco, Alireza Akbari
NPG Asia Materials 12, 24 (2020)
Charge density waves are ubiquitous phenomena in metallic transition metal dichalcogenides. In NbSe_2, 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-NbSe_2, 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.