Two-dimensional nonlinear dynamical response of the magnetoelectrically driven dimerized XXZ-chain

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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 light 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 occurring beyond the free XY-limit. 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.
Funding Information
  • DFG (247310070)
  • NSF (PHY-2210452)
  • Aspen Center for Physics

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