Charge density wave quantum critical point with strong enhancement of superconductivity

Abstract

Quantum critical points (QCPs), at which a second-order phase transition is continuously suppressed to zero temperature, are currently one of the central topics in solid-state physics. The strong interest emerges from observations of very unusual properties at QCPs such as the onset of unconventional superconductivity (SC) 3 . While QCPs found at the disappearance of magnetic order are quite common and intensively studied, a QCP that results from a structural transition is scarce and poorly investigated. Here, we report on the observation of a charge density wave (CDW) type of structural ordering in LuPt 2 In with a second-order transition at T CDW = 490 K. Substituting Pd for Pt suppresses T CDW continuously towards T = 0, leading to a QCP at 58% Pd substitution. We find a strong enhancement of bulk SC just at the QCP, pointing to a new type of interaction between CDW and SC.