Universal superconducting precursor in three classes of unconventional superconductors.

Pelc, D; Anderson, Z; Yu, B; Leighton, C; Greven, M · Nat Commun · 2019

basic_science · Level V

Where this comes from

Abstract

A pivotal challenge posed by unconventional superconductors is to unravel how superconductivity emerges upon cooling from the generally complex normal state. Here, we use nonlinear magnetic response, a probe that is uniquely sensitive to the superconducting precursor, to uncover remarkable universal behaviour in three distinct classes of oxide superconductors: strontium titanate, strontium ruthenate, and the cuprate high-T<sub>c</sub> materials. We find unusual exponential temperature dependence of the diamagnetic response above the transition temperature T<sub>c</sub>, with a characteristic temperature scale that strongly varies with T<sub>c</sub>. We correlate this scale with the sensitivity of T<sub>c</sub> to local stress and show that it is influenced by intentionally-induced structural disorder. The universal behaviour is therefore caused by intrinsic, self-organized structural inhomogeneity, inherent to the oxides' perovskite-based structure. The prevalence of such inhomogeneity has far-reaching implications for the interpretation of electronic properties of perovskite-related oxides in general.