We study the far from equilibrium prethermal dynamics of magnons in Heisenberg ferromagnets. We show that such systems exhibit universal self-similar scaling in momentum and time of the quasiparticle distribution function, with the scaling exponents independent of microscopic details or initial conditions. We argue that the SU(2) symmetry of the Hamiltonian, which leads to a strong momentum-dependent magnon-magnon scattering amplitude, gives rise to qualitatively distinct prethermal dynamics from that recently observed in Bose gases. We compute the scaling exponents using the Boltzmann kinetic equation and incoherent initial conditions that can be realized with microwave pumping of magnons. We also compare our numerical results with analytic estimates of the scaling exponents and demonstrate the robustness of the scaling to variations in the initial conditions. Our predictions can be tested in quench experiments of spin systems in optical lattices and pump-probe experiments in ferromagnetic insulators such as yttrium iron garnet.

中文翻译：

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海森堡铁磁体的普遍预热动力学

我们研究了海森堡铁磁体中的磁振子远非平衡的预热动力学。我们证明了这样的系统在准粒子分布函数的动量和时间上展现出通用的自相似标度，并且标度指数与微观细节或初始条件无关。我们认为，哈密顿量的SU（2）对称性导致了强烈的依赖于动量的磁振子-磁振子散射振幅，从而引起了与最近在玻色气体中观察到的定性不同的预热动力学。我们使用玻尔兹曼动力学方程和不相干的初始条件（使用磁振子的微波泵浦可以实现）来计算缩放指数。我们还将数值结果与缩放指数的解析估计进行了比较，并证明了缩放对初始条件变化的鲁棒性。我们的预测可以在光学晶格中的自旋系统的淬灭实验以及在铁磁绝缘子（如钇铁石榴石）中的泵浦探针实验中得到检验。