Holstein polarons, Rashba-like spin splitting and Ising superconductivity in electron-doped MoSe2

TL;DR

This paper investigates electron-phonon interactions in doped MoSe2, revealing polaron formation, spin splitting, and implications for superconductivity, providing experimental insights into theoretical models of layered TMDCs.

Contribution

It reports the first observation of polarons, Rashba-like spin splitting, and the crossover in spectral features in electron-doped MoSe2, advancing understanding of superconductivity mechanisms in TMDCs.

Findings

Polaron formation at alkali-dosed MoSe2 surface.

Rashba-like spin splitting caused by inversion symmetry breaking.

Crossover from phonon-like to plasmon-like spectral features with doping.

Abstract

Interaction between electrons and phonons in solids is a key effect defining physical properties of materials such as electrical and thermal conductivity. In transitional metal dichalcogenides (TMDCs) the electron-phonon coupling results in the creation of polarons, quasiparticles that manifest themselves as discrete features in the electronic spectral function. In this study, we report the formation of polarons at the alkali dosed MoSe2 surface, where Rashba-like spin splitting of the conduction band states is caused by an inversion-symmetry breaking electric field. In addition, we observe the crossover from phonon-like to plasmon-like polaronic spectral features at MoSe2 surface with increasing doping. Our findings support the concept of electron-phonon coupling mediated superconductivity in electron-doped layered TMDC materials, observed using ionic liquid gating technology. Furthermore, the discovered spin-splitting at the Fermi level could offer crucial experimental validation for theoretical models of Ising-type superconductivity in these materials.