Gate-tuned ambipolar superconductivity with strong pairing interaction in intrinsic gapped monolayer 1T'-MoTe2

TL;DR

This study demonstrates gate-tuned superconductivity in monolayer 1T'-MoTe2 with an intrinsic band gap, showing high transition temperatures and strong pairing interactions, surpassing BCS expectations.

Contribution

It reveals that electrostatic doping induces superconductivity in gapped monolayer MoTe2 with enhanced pairing interactions and critical fields exceeding BCS limits.

Findings

Superconductivity occurs near 7-8K for electrons and holes.

Critical magnetic field exceeds BCS Pauli limit.

Gap ratio indicates strong coupling beyond BCS weak-coupling.

Abstract

Gate tunable two-dimensional (2D) superconductors offer significant advantages when studying superconducting phase transitions. Here, we address superconductivity in exfoliated 1T'-MoTe2 monolayers with an intrinsic band gap of ~7.3 meV using electrostatic doping. Despite large differences in the dispersion of the conduction and the valence bands, superconductivity can be achieved easily for both electrons and holes. The onset of superconductivity occurs near 7-8K for both charge carrier types. This temperature is much higher than in bulk samples. Also the in-plane upper critical field is strongly enhanced and exceeds the BCS Pauli limit in both cases. Gap information is extracted using point-contact spectroscopy. The gap ratio exceeds multiple times the value expected for BCS weak-coupling. All these observations suggest a strong enhancement of the pairing interaction.