Spin-triplet superconductivity from excitonic effect in doped insulators.

Crépel, Valentin; Fu, Liang · Proc Natl Acad Sci U S A · 2022

basic_science · Level V

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Abstract

SignificanceWe present a mechanism for unconventional superconductivity in doped band insulators, where short-ranged pairing interaction arises from Coulomb repulsion due to virtual interband or excitonic processes. Remarkably, electron pairing is found upon infinitesimal doping, giving rise to Bose-Einstein condensate (BEC)-Bardeen-Cooper-Schrieffer (BCS) crossover at low density. Our theory explains puzzling behaviors of superconductivity and predicts spin-triplet pairing in electron-doped ZrNCl and WTe<sub>2</sub>.