Analytic Expression for Magnetic Activation Energy

Abstract

We theoretically investigate the magnetic activation energy of permanent magnets. Practically, it is widely used in a phenomenological form as ${\mathcal{F}}_{\mathrm{B}}(H_{\mathrm{ext}})={\mathcal{F}}_{\mathrm{B}}^0{\left(1-H_{\mathrm{ext}}/H_0\right)}^n,$ where ${\mathcal{F}}_{\mathrm{B}}^0$ is the activation energy in the absence of an external magnetic field $H_{\mathrm{ext}}$, $n$ is a real parameter, and $H_0$ is defined by the equation ${\mathcal{F}}_{\mathrm{B}}(H_0)=0$. We derive the general and direct expressions for these phenomenological parameters under the restriction of uniform rotation of magnetization and on the basis of the perturbative theory with respect to $H_{\mathrm{ext}}$. Further,we apply our results to Nd${}_2$Fe${}_{14}$B magnets and confirm the validity of the proposed method by comparing with the Monte Carlo calculations.

8 pages, 2 figures

References in corpus (7)

• Quantum Theory of Rare-Earth Magnets
• Monte Carlo analysis for finite temperature magnetism of Nd${}_2$Fe${}_{14}$B permanent magnet
• Thermal activation in permanent magnets
• Realization of the thermal equilibrium in inhomogeneous magnetic systems by the Landau-Lifshitz-Gilbert equation with stochastic noise, and its dynamical aspects
• Anisotropy of exchange stiffness based on atomic-scale magnetic properties in rare-earth permanent magnet Nd${}_2$Fe${}_{14}$B
• Theoretical evaluation on the temperature dependence of magnetic anisotropy constants of Nd2Fe14B - Effects of exchange field and crystal field strength -
• Power law analysis for temperature dependence of magnetocrystalline anisotropy constants of Nd${}_2$Fe${}_{14}$B magnets

Cited by in corpus (1)

• Temperature Dependence of Magnetocrystalline Anisotropy in Itinerant Ferromagnets