Manipulating superconductivity of 1T-TiTe2 by high pressure

Abstract

Superconductivity of transition metal dichalcogenide 1T-TiTe₂ under high pressure was investigated by first-principles calculations. Our results show that the superconductivity of 1T-TiTe₂ exhibits very different behavior under hydrostatic and uniaxial pressure. The hydrostatic pressure is harmful to the superconductivity, while the uniaxial pressure is beneficial to the superconductivity. The superconducting transition temperature T_C at ambient pressure is 0.73 K, and it reduces monotonously under the hydrostatic pressure to 0.32 K at 30 GPa, while T_C increases dramatically under the uniaxial pressure along the c axis. The established T_C of 6.34 K under the uniaxial pressure of 17 GPa, below which the structural stability is maintained, is above the liquid helium temperature of 4.2 K. The increase of the density of states at the Fermi level, the red-shift of the phonon density of states/Eliashberg spectral function F(ω)/α²F(ω), and the softening of the acoustic modes with pressure are considered as the main reasons that lead to the enhanced superconductivity under uniaxial pressure. In view of the previously predicted topological phase transitions of 1T-TiTe₂ under the uniaxial pressure (Q. Zhang et al., Phys. Rev. B: Condens. Matter Mater. Phys., 2013, 88, 155317), we consider 1T-TiTe₂ as a possible candidate in transition metal chalcogenides for exploring topological superconductivity.