A short note on spin pumping theory with Landau-Lifshitz-Gilbert   equation under quantum fluctuation; necessity for quantization of localized   spin
  We would like to point out the blind spots of the approach combining the spin pumping theory proposed by Tserkovnyak et al. with the Landau-Lifshitz-Gilbert equation; this method has been widely used for interpreting vast experimental results. The essence of the spin pumping effect is the quantum fluctuation. Thus, localized spin degrees of freedom should be quantized, i.e. be treated as magnons not as classical variables. Consequently, the precessing ferromagnet can be regarded as a magnon battery. This point of view will be useful for further progress of spintronics. 
Kouki Nakata
cond-mat.mes-hall cond-mat.quant-gas cond-mat.stat-mech cond-mat.str-el