1201.6316 (Andrew Sykes et al.)

Bloch-Redfield theory of high-temperature magnetic fluctuations in
interacting spin systems    [PDF]

Andrew Sykes, Dmitry Solenov, Dmitry Mozyrsky

We study magnetic fluctuations in a system of interacting spins on a lattice
at high temperatures and in the presence of a spatially varying magnetic field.
Starting from a microscopic Hamiltonian we derive effective equations of motion
for the spins and solve these equations self-consistently. We find that the
spin fluctuations can be described by an effective diffusion equation with a
diffusion coefficient which strongly depends on the ratio of the magnetic field
gradient to the strength of spin-spin interactions. We also extend our studies
to account for external noise and find that the relaxation times and the
diffusion coefficient are mutually dependent.

View original: http://arxiv.org/abs/1201.6316