Universality in the relaxation of spin helices under XXZ spin-chain dynamics

We describe the dynamics of a transverse spin-helix state - a product state with spatially rotating magnetization - under XXZ spin chain evolution. Due to experimental relevance we especially focus on magnetization dynamics. At long times the U(1) symmetry of the Hamiltonian is restored, leading to the decay of transverse magnetization, which can be described as an exponential decay of a spatially harmonic profile. We show that the dependence of the short- and intermediate-time decay timescale, which in principle depends on all different parameters, like the wave vector of the initial helix, the anisotropy, etc., can be described well by a single scaling function. We also briefly discuss the evolution of magnetization current. © 2023 American Physical Society.