Superconducting transition in a non-superconducting PrBa₂Cu₃O₇ film triggered by interfacial carrier injection

The discovery in 1986 of high-temperature superconductivity in cuprates above liquid nitrogen temperature brought about a new chapter in high-temperature superconductivity research, bringing applications that bit closer. However, how to further improve the superconducting transition temperature of high-temperature superconductors is a huge challenge in condensed matter physics and materials science. Recently, interface-enhanced high-temperature superconductivity in one-unit-cell FeSe film on a SrTiO₃ substrate has created a new avenue for improving the superconducting transition temperature. Here, a transition from an originally non-superconducting state to a superconducting state triggered by the interfacial injection of charge carriers was observed in a PrBa₂Cu₃O₇/Nb-doped SrTiO₃ heterostructure, and the non-superconducting to superconducting transition temperature increases with increase in the injection current. Current–voltage characteristics indicate that several conduction mechanisms coexist. In the proposed mechanism, the injected electrons are self-trapped in an unstable quasiconduction band which has a direct influence on the intrinsic properties, such as resistance and superconductivity, of the PrBa₂Cu₃O₇ film. Our findings offer an alternative strategy for manipulating the superconducting state in oxides by the injection of charge carriers through the oxide interfaces, and can also help us to understand the mechanism of high-temperature superconduction. (paper)