The soft-mode phonons mediated unconventional superconductivity in monolayer 1T'-WTe2

TL;DR

This paper investigates how soft-mode phonons facilitate unconventional superconductivity in electron-doped monolayer 1T'-WTe2, revealing a doping-dependent superconducting dome and anisotropic triplet pairing.

Contribution

It provides a theoretical explanation linking soft-mode phonons and Fermi surface nesting to superconductivity and unconventional pairing in doped 1T'-WTe2.

Findings

Superconductivity arises with electron doping due to soft-mode phonons.

A superconducting dome is observed related to Fermi surface nesting.

Superconducting state likely has equal-spin-triplet pairing.

Abstract

Recent experiments have tuned the monolayer 1T'-WTe2 to be superconducting by electrostatic gating. Here, we theoretically study the phonon-mediated superconductivity in monolayer 1T'-WTe2 via charge doping. We reveal that the emergence of soft-mode phonons with specific momentum is crucial to give rise to the superconductivity in electron-doping regime, whereas no such soft-mode phonons and no superconductivity emerge in hole-doping regime. We also find a superconducting dome, which can be attributed to the change of Fermi surface nesting condition as electron doping. By taking into account the experimentally established strong anisotropy of temperature-dependent upper critical field H_{c2} between the in-plane and out-of-plane directions, we show that the superconducting state probably has the unconventional equal-spin-triplet pairing in A_{u} channel of C_{2h} point group. Our studies provide a promising understanding to the doping dependent superconductivity and strong anisotropy of H_{c2} in monolayer 1T'-WTe2.