First-principles study of superconductivity in 2D and 3D forms of PbTiSe$_{2}$: Suppressed charge density wave in 1\emph{T}-TiSe$_{2}$

TL;DR

This study uses first-principles calculations to show that Pb intercalation suppresses charge density waves and induces superconductivity in 1T-TiSe2, with tunable properties and estimated critical temperatures.

Contribution

It provides a detailed first-principles analysis of how Pb intercalation affects charge density waves and induces superconductivity in 1T-TiSe2, revealing tunable superconducting properties.

Findings

Pb intercalation suppresses charge density wave instability.

PbTiSe2 is a phonon-mediated superconductor with Tc ~1.6-3.8 K.

Superconductivity is mainly due to vibrations of Pb and Se atoms.

Abstract

Layered 1$T$-TiSe$_{2}$ has attracted much interest for the competition of charge density wave (CDW) and superconductivity in its bulk and even monolayer forms. Here we perform first-principles calculations of the electronic structure, phonon dispersion, and electron-phonon coupling of the Pb-intercalated 1$T$-TiSe$_{2}$ in bulk and layered structures. Results show that upon the Pb atom intercalation, the CDW instability in 1$T$-TiSe$_{2}$ can be effectively suppressed, accompanied by the removal of the imaginary phonon modes at \textbf{q}$_{\rm{M}}$. The Pb 6\emph{p} orbitals occupy directly at the Fermi level, which hence intercalates the superconductivity. Both bulk and layered PbTiSe$_{2}$ are phonon-mediated superconductors, with estimated superconducting temperature $T_{c}$ to be $\sim$1.6-3.8 K. The main contribution to the electron-phonon coupling is from the vibrations of Pb and Se atoms. The superconducting related physical quantities are found tunable by varying Pb content.