Perspectives of stochastic micromagnetism of Nd2Fe14B and computation of thermally activated process

The thermal and dynamical properties Nd2Fe14B at finite temperatures are studied with anatomic model Hamiltonian.The temperature dependence of the magnetization including thereorientation transition was obtained successfully.Moreover, the atom-specific observationrevealed that the Nd magneticmoment decreases fastwith the temperature. Temperaturedependence of the domain wall structures was also obtained. Beside the static thermalproperties, dynamics of the magnetization in unfavorable magnetic field was studied bystochastic LLG equation and Monte Carlo method. The field and size-dependences of therelaxation time at finite temperatures are discussed including the effects of the dipole-dipoleinteraction.

 The present work was supported by the Elements Strategy Initiative Center for Magnetic Materials under the outsourcing project of MEXT. The authors thank the Supercomputer Center, Institute for Solid State Physics, The University of Tokyo, for the use of the facilities.