Field induced conducting state in Mott insulator

TL;DR

This paper demonstrates that a resonant staggered magnetic field can induce a conducting state in a Mott insulator by forming bound pairs, leading to unique dynamical behaviors under electric and quenching fields.

Contribution

It reveals a novel mechanism where external field modulation and electron correlation induce a conducting state in a Mott insulator, with detailed dynamical phenomena.

Findings

Bound pairs form under resonant staggered field with large energy bandwidth.

Fast bound pair Bloch oscillation occurs under electric field, single electrons are frozen.

Quenching resonant field transforms Mott insulator into doublon conducting state.

Abstract

Electron--electron repulsion, on the one hand, can result in bound pair, which has heavy effective mass. On the other hand, it is also the cause of Mott insulator. We study the effect of a staggered magnetic field on a Hubbard model. We find that a bound pair with large energy bandwidth can be formed under the resonant staggered field, being the half of Hubbard repulsion strength. Accordingly, the system exhibits following dynamical behaviors: (i) When an electric field is applied, fast bound pair Bloch oscillation occurs, while a single electron is frozen. (ii) When a quenching resonant field is applied to an initial antiferromagnetic Mott insulating state, the final state becomes doublon conducting state manifested by the non-zero $\eta$ correlator and large charge fluctuation. Our finding indicates that the cooperation of electron-electron correlation and modulated external field can induce novel quench dynamics.