Electronic Orbital Currents and Polarization in Mott Insulators

TL;DR

This paper reveals that Mott insulators can host spontaneous electric currents and charge distributions in their ground state, challenging the traditional view that charge degrees are frozen, and shows these effects influence dielectric and magnetic properties.

Contribution

It demonstrates the existence of spontaneous circular currents and charge distributions in Mott insulators, linking these to novel dielectric and magnetic phenomena.

Findings

Presence of spontaneous circular electric currents in ground states

Charge distributions affecting dielectric and magnetic functions

Potential for negative refraction index phenomena

Abstract

The standard view is that at low energies Mott insulators exhibit only magnetic properties while charge degrees of freedom are frozen out as the electrons become localized by a strong Coulomb repulsion. We demonstrate that this is in general not true: for certain spin textures {\it spontaneous circular electric currents} or {\it nonuniform charge distribution} exist in the ground state of Mott insulators. In addition, low-energy ``magnetic'' states contribute comparably to the dielectric and magnetic functions $\epsilon_{ik}(\omega)$ and $\mu_{ik}(\omega)$ leading to interesting phenomena such as rotation the electric field polarization and resonances which may be common for both functions producing a negative refraction index in a window of frequencies.