1986/06/15 by P. Gaunt · 1 citation
Physics and Astronomy · Materials Science · Chemistry · #Theoretical and Computational Physics #Magnetic properties of thin films #Material Dynamics and Properties #Activation energy #Condensed matter physics #Viscosity #Magnetization #Magnetic field #Magnetic energy #Magnetic domain #Boltzmann constant #Single domain #Physics #Domain wall (magnetism) #Materials science #Thermodynamics #Chemistry #Quantum mechanics
paper · doi:10.1063/1.336671
openalex publication_date 1986/06/15 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/04
Magnetic viscosity arises when the activation energy E required to produce a change in mangetization is provided thermally. Activation energy functions for single domain particles and materials with ‘‘strong’’ and ‘‘weak’’ domain-wall pinning are discussed. The magnetic viscosity parameter Sv, given by kT(∂E/∂H)−1T, where kT is the Boltzmann energy and H is the magnetic field, is shown to be proportional to kT/(v Ms), where Ms is the spontaneous magnetization and v is the activation volume swept out as the energy barrier is overcome. For single domain particles and strong domain-wall pinning the constant of proportionality is one while for weak pinning it is 1/2. The generality of this simple relationship is shown to be independent of the details of the activation model.