Two-dimensional nonlinear dynamical response of the magnetoelectrically driven dimerized spin-$1{/}2$ chain

TL;DR

This paper investigates the complex nonlinear dynamical response of a dimerized spin-1/2 chain under electric fields, revealing features like galvanoelectric responses and the impact of vertex corrections on spinon excitations.

Contribution

It provides analytical expressions for the nonlinear response in the XY-limit and explores vertex correction effects in the XXZ model, highlighting new spectral phenomena.

Findings

Identification of strong galvanoelectric features in the 2D response plane

Vertex corrections significantly alter the spinon density of states

Potential formation of in-gap bound states due to renormalized light-matter coupling

Abstract

A study of the dynamical two-dimensional (2D) nonlinear response of the dimerized spin-$1{/}2$ chain to external electric fields is presented. The coupling of the spin system to those fields is set to arise from the inverse Dzyaloshinskii-Moriya interaction. In the XY-limit, we provide analytical expressions for the second-order nonlinear dynamical response function. Apart from multi spinon continua, this response displays a strong antidiagonal, i.e. galvanoelectric, feature in the 2D frequency plane. This allows to read off scattering rates of the fractional spinon excitations. For the XXZ-case, we focus on the interaction-driven renormalization of the light-matter coupling by considering vertex corrections which are induced by the zz-exchange. We show this renormalization to modify the spinon joint density of states significantly, potentially allowing for the formation of in-gap bound states. As a result, the vertex corrected light-matter coupling can induce a dramatic spectral weight transfer to lower energies for the dynamical response function within the 2D frequency plane.