Electrical Breakdown of Excitonic Insulators

Explore the groundbreaking research on a new electrical breakdown mechanism for exciton insulators in the BCS limit during this 1 hour and 13 minute lecture. Delve into the proposed "many-body breakdown" mechanism, which fundamentally differs from the traditional Zener breakdown observed in band insulators. Examine how this novel mechanism arises from the instability of the many-body ground state for exciton condensation, caused by the strong competition between polarization and condensation energies in the presence of an electric field. Investigate the BCS-type trial wave function under finite electric fields used to study the many-body breakdown numerically. Analyze the two different types of electric breakdown behavior revealed by the research, depending on the system size relative to a critical value. Learn about the intermediate tunnelling phase and its disappearance in smaller systems, as well as the sudden disappearance of the local gap leading to an "off-on" feature in the current-voltage curve. Gain insights into how this research provides a straightforward method to distinguish excitonic insulators from normal insulators, advancing our understanding of condensed matter physics.