Superconductivity in an extreme strange metal

TL;DR

This paper reports the discovery of superconductivity emerging from an extreme strange metal state with linear resistivity over a wide temperature range, suggesting a new pairing mechanism linked to charge localization-delocalization transitions.

Contribution

It provides experimental evidence of superconductivity in an extreme strange metal and proposes a novel pairing mechanism related to charge dynamics.

Findings

Superconductivity condenses out of an extreme strange metal state.

Linear resistivity observed over 3.5 orders of magnitude in temperature.

Proposed pairing mechanism involves charge localization-delocalization modes.

Abstract

Some of the highest-transition-temperature superconductors across various materials classes exhibit linear-in-temperature `strange metal' or `Planckian' electrical resistivities in their normal state. It is thus believed by many that this behavior holds the key to unlock the secrets of high-temperature superconductivity. However, these materials typically display complex phase diagrams governed by various competing energy scales, making an unambiguous identification of the physics at play difficult. Here we use electrical resistivity measurements into the micro-Kelvin regime to discover superconductivity condensing out of an extreme strange metal state -- with linear resistivity over 3.5 orders of magnitude in temperature. We propose that the Cooper pairing is mediated by the modes associated with a recently evidenced dynamical charge localization-delocalization transition, a mechanism that may well be pertinent also in other strange metal superconductors.