Charge-spin-orbital dynamics of one-dimensional two-orbital Hubbard model

TL;DR

This study investigates the real-time charge-spin-orbital dynamics in a one-dimensional two-orbital Hubbard model using time-dependent density-matrix renormalization group, revealing distinct propagation behaviors of holons and doublons due to pair hopping.

Contribution

It introduces a detailed analysis of charge-excited state dynamics in a multi-orbital system, highlighting the role of pair hopping in charge propagation.

Findings

Holon and doublon propagate at different speeds.

Pair hopping enables electron transfer between orbitals.

Charge dynamics are influenced by multi-orbital interactions.

Abstract

We study the real-time evolution of a charge-excited state in a one-dimensional $e_{\rm g}$-orbital degenerate Hubbard model, by a time-dependent density-matrix renormalization group method. Considering a chain along the $z$ direction, electrons hop between adjacent $3z^2-r^2$ orbitals, while $x^2-y^2$ orbitals are localized. For the charge-excited state, a holon-doublon pair is introduced into the ground state at quarter filling. At initial time, there is no electron in a holon site, while a pair of electrons occupies $3z^2-r^2$ orbital in a doublon site. As the time evolves, the holon motion is governed by the nearest-neighbor hopping, but the electron pair can transfer between $3z^2-r^2$ orbital and $x^2-y^2$ orbital through the pair hopping in addition to the nearest-neighbor hopping. Thus holon and doublon propagate at different speed due to the pair hopping that is characteristic of multi-orbital systems.