Collective phenomena, such as charge/spin density waves and superconductivity, may change abruptly at the surface or in single layers of layered materials, whose observation may be affected by epitaxial strain. In Niobium diselenide, a stripe charge density wave, in place of a usual triangular one, has been observed at the surface, but not in single-layer. Phonon calculations and total energy calculations shed light on the intrinsic nature of the periodic lattice distortions, finding good agreement with experimental observations of phase separation between triangular and stripe phases, attributing to isotropic compressive strain the emergence of the latter.
- Fabrizio Cossu
- Krisztián Palotás
- Alireza Akbari
