Quantum Brownian motion for magnets

@article{Anders2022QuantumBM,
  title={Quantum Brownian motion for magnets},
  author={Janet Anders and C R J Sait and Simon A. R. Horsley},
  journal={New Journal of Physics},
  year={2022},
  volume={24}
}
Spin precession in magnetic materials is commonly modelled with the classical phenomenological Landau–Lifshitz–Gilbert (LLG) equation. Based on a quantized three-dimensional spin + environment Hamiltonian, we here derive a spin operator equation of motion that describes precession and includes a general form of damping that consistently accounts for memory, coloured noise and quantum statistics. The LLG equation is recovered as its classical, Ohmic approximation. We further introduce resonant… 

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