Nematic-fluctuation-mediated superconductivity in CuxTiSe2

TL;DR

This study uncovers nematic fluctuations in CuxTiSe2 and shows their evolution with Cu doping, suggesting nematic phase transitions may enhance superconductivity in this material.

Contribution

It provides the first evidence of nematic fluctuations in TiSe2 and links their suppression and sign change with superconductivity tuning via Cu intercalation.

Findings

Nematic fluctuations follow a Curie-Weiss law at high temperature.

T* decreases and approaches zero as superconductivity is optimized.

Further Cu doping reverses T* sign and suppresses superconductivity.

Abstract

The interplay among electronic nematicity, charge density wave, and superconductivity in correlated electronic systems has induced extensive research interest. Here, we discover the existence of nematic fluctuations in TiSe2 single crystal and investigate its evolution with Cu intercalation. It is observed that the elastoresistivity coefficient mEg exhibits a divergent temperature dependence following a Curie-Weiss law at high temperature. Upon Cu intercalation, the characteristic temperature T* of nematic fluctuation is progressively suppressed and becomes near zero when the superconductivity is optimized. Further intercalation of Cu leads to the sign change of T* and the suppression of superconductivity. These results strongly indicate that nematic phase transition may play a vital role in enhancing superconductivity in CuxTiSe2. Therefore, CuxTiSe2 provides a unique material platform to explore the nematic-fluctuation-mediated superconductivity.