Phase Separation Induced by Symmetric Monocycle Optical Pulse in Extended Hubbard Models

TL;DR

This study explores how symmetric monocycle optical pulses can induce phase separation and effective attractive interactions in extended Hubbard models, revealing potential for controlling electron dynamics in correlated systems.

Contribution

It demonstrates that large-amplitude symmetric monocycle pulses can induce negative-temperature states and phase separation in extended Hubbard models, using both exact diagonalization and Hartree-Fock methods.

Findings

Negative-temperature states are formed under strong optical pulses.

Effective attractive interactions emerge from initially repulsive models.

Charge-rich and charge-poor phase separation occurs due to induced attraction.

Abstract

Many-electron dynamics induced by a symmetric monocycle electric-field pulse of large amplitude is theoretically investigated in one- and two-dimensional half-filled extended Hubbard models on regular lattices (i.e., without dimerization) using the exact diagonalization method for small systems and the Hartree-Fock approximation for large systems. The formation of a negative-temperature state and the change from repulsive interactions to effective attractive interactions are shown to be realized for a wide region of the field amplitude and the excitation energy. For a nonnegligible intersite repulsive interaction, the numerical results are consistent with the fact that the phase separation between charge-rich and charge-poor regions is caused by the corresponding effective attraction.