Spin dynamics simulations of excitations and critical dynamics in RbMnF_3

TL;DR

This paper uses spin-dynamics simulations to study the dynamic and critical behavior of RbMnF_3, revealing the crossover from hydrodynamic to critical regimes and estimating the dynamic critical exponent.

Contribution

It introduces a new simulation algorithm based on Suzuki-Trotter decompositions for analyzing spin dynamics in RbMnF_3, providing detailed comparisons with experimental data.

Findings

Estimated dynamic critical exponent z=1.43±0.03

Observed crossover from hydrodynamic to critical behavior

Good agreement with recent experimental results

Abstract

Spin-dynamics simulations have been used to investigate the dynamic behavior of RbMnF_3, treating it as a classical Heisenberg antiferromagnet on a simple cubic lattice. Time-evolutions of spin configurations were determined numerically from coupled equations of motion for individual spins using a new algorithm which is based on Suzuki-Trotter decompositions of exponential operators. The dynamic structure factor was calculated from the space- and time-displaced spin-spin correlation function. The crossover from hydrodynamic to critical behavior of the dispersion curve and spin-wave half-width was studied as the temperature was increased towards the critical value. The dynamic critical exponent was estimated to be z=(1.43\pm 0.03), which is slightly lower than the dynamic scaling prediction, but in good agreement with a recent experimental value. Comparisons are made of both the dispersion curve and the lineshapes obtained from our simulations with very recent experimental results for RbMnF_3 are presented.