Suerpconductivity in CuxTiSe2

Charge density wave transitions are frequent occurrences in transition metal chalcogenides due to electronic instabilities engendered by their low structural dimensionality. The layered dichalcogenides are the most, well-studied examples, with TiSe2 one of the first CDW-bearing materials known. That CDW and superconducting states compete for stability has long been held and explored, and yet no chemical system has been previously reported where finely controlled chemical tuning allows the competition between CDW formation and superconductivity to be studied in detail. Here we report how, upon controlled Cu intercalation of TiSe2 to yield CuxTiSe2, the CDW transition is continuously suppressed, and a new superconducting state emerges near x = 0. 04, with a maximum Tc of 4.15 K found at x = 0.08. CuxTiSe2 thus provides the first opportunity to study the CDW-Superconductivity transition in detail through an easily-controllable chemical parameter, and will provide new insights into the behavior of correlated electron systems.