Topological suppression of the charge-density-wave transition in TiSe2

Abstract

The influence of the selective distortion of the Se and Ti sublattices on the stability of the charge-density-wave (CDW) state has been studied. The selective distortion has been obtained in two ways: by Mn or Cr intercalation, which differ in the selective hybridization between Mn 3d/Se 4p and Cr 3d/Ti 3d orbitals, and by the plastic uniaxial deformation of the TiSe2 single crystals. Plastic deformation generates defects in the Se sublattice, which create the difference between the nearest neighbor positions. It is found that the distortions of the Se sublattice make impact up to 1000 times more on the CDW state stability than those of the Ti sublattice. The effect is related to the distortion of the spatial coherence of the Se 4p-orbitals. The critical size of the coherence area, below which the CDW becomes unstable structure and loses a long-range-order, has been estimated. It is found that such a kind of suppression does not change the temperature of the CDW transition but gradually decreases its amplitude.