Dynamic correlations of frustrated quantum spins from high-temperature expansion

Abstract: For quantum spin systems in equilibrium, the dynamic structure factor (DSF) is among the most feature-packed experimental observables. However, from a theory perspective it is often hard to simulate in an unbiased and accurate way, especially for frustrated and high-dimensional models at intermediate temperature. We address this challenge by introducing a dynamic extension of the high-temperature expansion as an efficient numerical approach to the DSF for arbitrary lattices. We focus on the nearest-neighbor Heisenberg model and spin-lengths S=1/2 and 1. We present a user-friendly numerical implementation and provide comprehensive benchmarks on spin chains. As applications we treat a variety of frustrated two- and three dimensional antiferromagnets. In particular we shed new light on the anomalous intermediate temperature regime of the S=1/2 triangular lattice model and reproduce the DSF measured recently for a S=1 pyrochlore material.