Excitonic wave-packet evolution in a two-orbital Hubbard model chain: A real-time real-space study

TL;DR

This study investigates the real-time evolution of excitonic wave-packets in a two-orbital Hubbard model, revealing charge-spin and spin-orbit separation, and how inter-orbital interactions influence exciton dynamics.

Contribution

It provides the first real-space, real-time analysis of excitonic wave-packet evolution in a two-orbital Hubbard model using tDMRG, highlighting spin-orbit separation and tunable orbiton velocity.

Findings

Evidence of charge-spin and spin-orbit separation in real-space.

Orbiton velocity can be tuned by inter-orbital interactions.

Fractionalized spinons observed with spin-flip excitations.

Abstract

Motivated by experimental developments introducing the concept of spin-orbit separation, we study the real-space time evolution of an excitonic wave-packet using a two-orbital Hubbard model. The exciton is created by exciting an electron from a lower energy half-filled orbital to a higher energy empty orbital. We carry out the real-time dynamics of the resulting excitonic wave-packet, using the time-dependent density matrix renormalization group method. We find clear evidence of charge-spin and spin-orbit separation in real-space, by tracking the time evolution of local observables. We show that the velocity of the orbiton can be tuned by varying the inter-orbital interactions. We also present a comparative study of a hole (in one orbital) and exciton (in two orbitals) dynamics in one-dimensional systems. Moreover, we analyze the dynamics of an exciton with spin-flip excitation, where we observe fractionalized spinons induced by Hund's interaction.