Coexistence of resistance oscillations and the anomalous metal phase in a lithium intercalated TiSe2 superconductor

Menghan Liao,Ding Zhang,Mohsin Rafique,Qi-Kun Xue,Runan Shang,Hao Zhang,Heng Wang,Lexian Yang,Yuying Zhu

doi:10.1038/s41467-021-25671-8

Abstract

Superconductivity and charge density wave (CDW) appear in the phase diagram of a variety of materials including the high-Tc cuprate family and many transition metal dichalcogenides (TMDs). Their interplay may give rise to exotic quantum phenomena. Here, we show that superconducting arrays can spontaneously form in TiSe2–a TMD with coexisting superconductivity and CDW—after lithium ion intercalation. We induce a superconducting dome in the phase diagram of LixTiSe2 by using the ionic solid-state gating technique. Around optimal doping, we observe magnetoresistance oscillations, indicating the emergence of periodically arranged domains. In the same temperature, magnetic field and carrier density regime where the resistance oscillations occur, we observe signatures for the anomalous metal—a state with a resistance plateau across a wide temperature range below the superconducting transition. Our study not only sheds further insight into the mechanism for the periodic electronic structure, but also reveals the interplay between the anomalous metal and superconducting fluctuations.

Highlights

Superconductivity and charge density wave (CDW) appear in the phase diagram of a variety of materials including the high-Tc cuprate family and many transition metal dichalcogenides (TMDs)
Positive back-gating above a threshold voltage induces lithium ion intercalation
To understand the emergence of anomalous metal (AM) in a relatively thick sample, we put together the data obtained with the two methods—(1) sweeping B at fixed T and (2) varying T at fixed B—in Fig. 4c and Supplementary Fig. 17

Summary

Introduction

Superconductivity and charge density wave (CDW) appear in the phase diagram of a variety of materials including the high-Tc cuprate family and many transition metal dichalcogenides (TMDs) Their interplay may give rise to exotic quantum phenomena. At a still lower temperature scale, a superconducting dome—with a maximal transition temperature Tc0 ranging from 1.8 to 4.2 K—can be realized via chemical intercalation or applying pressure to the bulk material of TiSe22,4,12,13 Such a superconducting dome has been observed in TiSe2 in the two-dimensional (2D) limit by using the ionic liquid gating technique[6]. Of particular interest, are the peculiar magnetoresistance oscillations in such an ultrathin superconductor It indicates that a spatially periodic superconducting structure can form spontaneously. Our study suggests that periodically arranged domains may contribute to the emergence of the AM

Methods

Results

Conclusion