Spinon shift current in a noncentrosymmetric quantum spin chain

TL;DR

This paper demonstrates that spinon excitations in a noncentrosymmetric quantum spin chain can generate a bulk photovoltaic effect via a shift current mechanism, confirmed through real-time simulations.

Contribution

It introduces the concept of spinon shift current, showing that spinon excitations can induce direct current in a quantum spin chain under light irradiation.

Findings

Spinon excitations are the origin of the direct current generation.

The bulk photovoltaic effect is driven by electric polarization carried by spinons.

The study confirms the spinon shift current mechanism in a 1D XXZ model.

Abstract

We theoretically study direct current generation in a quantum spin chain induced by spinon excitations by light irradiation. We consider a s=1/2 1D antiferromagnetic XXZ model with magnetoelectric coupling that describes multiferroics with broken inversion symmetry. We perform the real-time simulation using infinite time-evolving block decimation (iTEBD), and demonstrate the direct current generation under light irradiation. By comparing the second order nonlinear conductivity and the two-spinon excitation spectra of 1D XXZ model, we confirm that the spinon excitations are the origin for the direct current generation in the quantum spin chain. We find that the bulk photovoltaic effect is driven by electric polarization carried by the spinons through the shift current mechanism, and thus is regarded as ``the spinon shift current''.