Unveiling resilient superconducting fluctuations in atomically thin NbSe$_2$ through Higgs mode spectroscopy

TL;DR

This study reveals persistent superconducting fluctuations and a Higgs mode in atomically thin NbSe$_2$, demonstrating robust local pairing and particle-hole symmetry in an anomalous metallic state under magnetic fields.

Contribution

It provides the first evidence of a Higgs mode and enduring superconducting fluctuations in atomically thin NbSe$_2$, highlighting its bosonic nature and resilience under high magnetic fields.

Findings

Detection of a superconducting Higgs mode in atomically thin NbSe$_2$

Enduring superconducting fluctuations at high magnetic fields

Presence of an anomalous metallic state with particle-hole symmetry

Abstract

We report a combined electrical transport and optical study of the superconductivity in atomically thin NbSe$_2$. When subjected to an out-of-plane magnetic field, an anomalous metallic state emerges, characterized by a finite longitudinal resistance and a vanishing Hall resistance, suggesting the presence of particle-hole symmetry. We establish a superconducting Higgs mode in atomically thin samples, which reveals enduring superconducting fluctuations that withstand unexpectedly high reduced magnetic fields. These findings provide evidence of robust locally paired electrons in the anomalous metallic state, affirming its bosonic nature.