Possible High temperature Superconductivity above 200K mediated by Bose Einstein Condensation of exciton

TL;DR

This paper reports the first experimental realization of exciton-mediated superconductivity with a transition temperature exceeding 200K, facilitated by Bose-Einstein condensation of excitons, revealing new mechanisms for high-temperature superconductivity.

Contribution

It demonstrates exciton-mediated superconductivity from an exciton insulator with a transition temperature above 200K, and uncovers the role of BEC and the Andreev-Bashkin effect in this phenomenon.

Findings

Transition temperature exceeds 200 K.

Observation of a resistivity transition indicating superconductivity.

Identification of the Andreev-Bashkin effect in exciton BEC superfluid.

Abstract

Exciton mediated superconductor is a fascinating quantum phase of matter that occurs when excitons become the dominant excitation in materials, which is also very promising for high temperature superconductor. However, there is no experimental report of exciton mediated superconductivity. Herein, we realize exciton mediated superconductivity from exciton insulator, where the onset transition temperature can reach larger than 200 K. More profoundly, Bose-Einstein condensation (BEC) of exciton can facilitate the formation of exciton insulator and a transition happened from extremely high resistivity of 107 {\Omega} at 153.5 K to 100 {\Omega} at 125 K, indicating a superconducting transition. The resistance of exciton mediated superconductivity can not be absolutely reach zero possibly as a result of drag effect between electrons/holes and excitons. We reveal one rule for exciton mediated superconductivity is that the resistivity is an inverse linear function of the current through the BEC superfluid state, which should be ascribed to the Andreev-Bashkin effect, which reflects the coupling between the BEC state of exciton and Cooper pairs mediated by excitons. Furthermore, a record transition temperature above 200 K has been found for one superconducting sample, which shows the Josephson oscillation dominated by a pendulum-like equation caused by the quantum coupling between superconductor and BEC superfluid of exciton.