Superconductivity in Cu_xTiSe_2

TL;DR

This study demonstrates how controlled copper intercalation in TiSe_2 suppresses charge density waves and induces superconductivity, enabling detailed exploration of the transition between these states in a tunable material.

Contribution

It introduces Cu_xTiSe_2 as the first chemically tunable system to study the competition between charge density waves and superconductivity.

Findings

CDW transition is continuously suppressed with Cu intercalation.

Superconductivity emerges near x=0.04 with a maximum T_c of 4.15 K at x=0.08.

Provides a new platform for studying correlated electron phenomena.

Abstract

Charge density waves (CDWs) are periodic modulations of the conduction electron density in solids. They are collective states that arise from intrinsic instabilities often present in low dimensional electronic systems. The layered dichalcogenides are the most well-studied examples, with TiSe_2 one of the first CDW-bearing materials known. The competition between CDW and superconducting collective electronic states at low temperatures has long been held and explored, and yet no chemical system has been previously reported where finely controlled chemical tuning allows this competition to be studied in detail. Here we report how, upon controlled intercalation of TiSe_2 with Cu to yield Cu_xTiSe_2, the CDW transition is continuously suppressed, and a new superconducting state emerges near x = 0.04, with a maximum T_c of 4.15 K found at x = 0.08. Cu_xTiSe_2 thus provides the first opportunity to study the CDW to Superconductivity transition in detail through an easily-controllable chemical parameter, and will provide new insights into the behavior of correlated electron systems.