Anomalous quantum metal in a 2D crystalline superconductor with intrinsic electronic non-uniformity

TL;DR

This study observes a superconducting to quantum metal transition in a 2D crystalline superconductor, revealing a field-driven crossover and the influence of coexisting quantum orders, advancing understanding of quantum phases in 2D materials.

Contribution

It reports the first observation of SQMT in a 2D ion-gel gated superconductor with intrinsic electronic non-uniformity, highlighting the role of fluctuating orders.

Findings

Identification of a field-induced crossover between Bose quantum metal and vortex quantum creeping.

Evidence of interplay between superconducting and charge density wave fluctuations.

Gate-tunable 1T-TiSe2 as a platform for studying quantum metal transitions.

Abstract

The details of the superconducting to quantum metal transition (SQMT) at T=0 are an open problem that invokes much interest in the nature of this exotic and unexpected ground state1-3. However, the SQMT was not yet investigated in a crystalline 2D superconductor with coexisting and fluctuating quantum orders. Here, we report the observation of a SQMT in 2D ion-gel gated 1T-TiSe24, driven by magnetic field. A field-induced crossover between Bose quantum metal and vortex quantum creeping with increasing field is observed. We discuss the interplay between superconducting and CDW fluctuations (discommensurations) and their relation to the anomalous quantum metal (AQM) phase. From our findings, gate-tunable 1T-TiSe2 emerges as a privileged platform to scrutinize, in a controlled way, the details of the SQMT, the role of coexisting fluctuating orders and, ultimately, obtain a deeper understanding of the fate of superconductivity in strictly two-dimensional crystals near zero temperature.