Photo-induced charge, spin, and orbital order in the two-orbital extended Hubbard model

TL;DR

This paper explores how ultrafast photo-doping can induce and control hidden charge, spin, and orbital orders in a two-orbital extended Hubbard model, revealing nonequilibrium phases with potential for ultrafast device applications.

Contribution

It demonstrates the emergence of tunable hidden orders out of nonequilibrium charge-ordered states using dynamical mean field theory, highlighting new nonequilibrium magnetic structures.

Findings

Hidden orders are tunable via photo-doping.

Nonequilibrium states resemble Kugel-Khomskii order.

Different magnetic structures emerge out of charge order.

Abstract

Nonequilibrium control of electronically ordered hidden phases may lead to the development of ultrafast switches and memory devices. In this study, we demonstrate tunable hidden orders in the photo-doped two-orbital extended Hubbard model. Using steady-state nonequilibrium dynamical mean field theory, we clarify the coexistence and interplay of nonthermal charge, spin, and orbital order. The hidden state at low effective temperature and sufficiently high photo-doping is reminiscent of Kugel-Khomskii order in the two-orbital Hubbard model at $\frac{1}{4}$ and $\frac{3}{4}$ filling, but it emerges out of a nonequilibrium charge ordered state and exhibits a different magnetic structure. A low-energy effective Hamiltonian is used to analyze the exchange processes which stabilize the nonthermal order.