Semi-quantum spin dynamics

SpeakerJoe Barker (University of Tohoku, Japan)
Time5pm on 20th June 2017

The use of classical Heisenberg models to understand the dynamical and thermodynamical properties of magnetic materials is now common place. Hamiltonians can be parameterised in exquisite detail from first principles or neutron scattering measurements. However there are serious issues with even a qualitative comparison with experiments and theory because of the disregard of quantum effects. The differences can be especially large in the low temperature regime which are often required for experiments. We present a modified approach which obeys quantum statistics but retains the classical spin vectors which make this approach easy to use and useful for dynamics. This makes a distinction between the local quantum effects (spin quantization) and the collective quantum effect (magnon statistics). The results show an excellent agreement with theory and experiments allowing truly quantitative calculations to be performed.