# Enhanced electron-phonon interaction in multi-valley materials

## TL;DR

This paper reveals a new mechanism that significantly enhances electron-phonon interactions in multi-valley materials, with implications for superconductivity, supported by combined theoretical and experimental evidence.

## Contribution

It identifies a phonon-induced out-of-phase energy shift mechanism that strengthens electron-phonon coupling in multi-valley materials, a novel insight not previously understood.

## Key findings

- Enhanced electron-phonon coupling observed in transition-metal dichalcogenides
- Mechanism reduces electrostatic screening via inter-valley charge transfer
- Potential relevance to superconductivity phenomena

## Abstract

Through a combined theoretical and experimental effort, we uncover a yet unidentified mechanism that strengthens considerably electron-phonon coupling in materials where electron accumulation leads to population of multiple valleys. Taking atomically-thin transition-metal dichalcogenides as prototypical examples, we establish that the mechanism results from a phonon-induced out-of-phase energy shift of the different valleys, which causes inter-valley charge transfer and reduces the effectiveness of electrostatic screening, thus enhancing electron-phonon interactions. The effect is physically robust, it can play a role in many materials and phenomena, as we illustrate by discussing experimental evidence for its relevance in the occurrence of superconductivity. (short abstract due to size limitations - full abstract in the manuscript)