Periodic Drive Induced Half-Metallic Phase in Insulators and Correlated Metals

TL;DR

This paper introduces a non-equilibrium method using periodic driving of the Hubbard model to induce a stable half-metallic phase, with potential applications in spintronics and quantum technologies.

Contribution

It demonstrates that periodic driving can transform a simple Hubbard model into a stable, ferrimagnetic half-metallic phase, a novel approach in non-equilibrium condensed matter physics.

Findings

Periodic drive induces staggered hopping and potential, stabilizing half-metallicity.

The phase is stable over large time scales and potentially perpetually under strong drive.

The method offers a new route for controlling electronic phases in correlated materials.

Abstract

Non-equilibrium control of electronic properties in condensed matter systems can result in novel phenomena. In this work, we provide a novel non-equilibrium route to realize half-metallic phases. We explore the periodically driven Hubbard model on a bipartite lattice and demonstrate that a periodic drive can transform a weakly interacting metal into a ferrimagnetic half-metal. We consider a Fermi-Hubbard model with only nearest-neighbour hopping and stabilize the elusive phase simply by driving the site potentials periodically. The drive induces staggered second and third-neighbor hopping and a staggered potential between two sublattices in the Floquet Hamiltonian, whose ground state is explored in this work. Close to the dynamical freezing point, due to the suppression of nearest neighbor hopping in the driven system, an effective enhancement of various terms in the Floquet Hamiltonian, including the e-e interactions, occurs. This helps in stabilizing a broad ferrimagnetic half-metallic phase for a wide range of system parameters. The half-metallic phase achieved in the presence of high drive frequency should be stable for exponentially large time scales in drive frequency and could be perpetually stable beyond a strong enough drive amplitude owing to dynamical freezing. It can hence have potential applications in stable spintronics and other upcoming quantum technologies.