Superconductivity in Cu-doped TiSe₂: A first-principles calculation

We present the superconducting properties of Cu-doped TiSe₂ materials based on first-principles calculations. Experimental study of Cu intercalated 1T-TiSe₂ under various copper doping concentrations (x = 0.04 – 0.10) has been investigated extensively. Such study has shown that as doping concentrations increase charge density wave is steadily suppressed until about x = 0.04 where a dome-shaped superconductivity emerges with maximum T_c of 4.15 K at x = 0.08 [1]. In order to understand this observation theoretically, we perform first-principles calculations based on density functional theory and density functional perturbation theory incorporated with maximally localized Wannier functions. We calculate the electronic structures at various doping concentrations by modeling doping using virtual crystal approximation. Also, we estimate the superconducting T_c by calculating the electron-phonon coupling and the Eliashberg spectral function. Further, we analyze all possible phonon modes in Cu_xTiSe₂ and ascertain dominant modes contributing to the superconductivity.
Reference
1. E. Morosan, H. W. Zandbergen, B. S. Dennis, J. W. G. Bos, Y. Onose, T. Klimczuk, A. P. Ramirez, N. P. Ong and R. J. Cava. Superconductivity in Cu_xTiSe₂. Nature Physics 2, 544 – 550 (2006).