Thermal and surface anisotropy effects on the magnetization reversal of a nanocluster

Abstract

The relaxation rate and temperature-dependent switching field curve of a spherical magnetic nanocluster are calculated by taking into account the effect of surface anisotropy via an effective anisotropy model. In particular, it is shown that surface anisotropy may change the thermally activated magnetization reversal by more than an order of magnitude, and that temperature-dependent switching field curves noticeably deviate from the Stoner-Wohlfarth astroid. With recent and future $\mu$-SQUID measurements in mind, we indicate how comparison of our results with experimental data on isolated clusters may allow one to obtain valuable information on surface anisotropy.

arXiv comment8 pages, 3 eps figures (Oral communication at ICFPM, Rome 9-12/10/07, by H. Kachkachi)

References in corpus (7)

• Magnetic Anisotropy of a Single Cobalt Nanoparticle
• Surface contribution to the anisotropy of magnetic nanoparticles
• Effective anisotropies and energy barriers of magnetic nanoparticles with Neel surface anisotropy
• Hysteretic properties of a magnetic particle with strong surface anisotropy
• Surface-induced cubic anisotropy in nanomagnets
• Statistical Mechanics of Nonuniform Magnetization Reversal
• Effect of exchange interaction on superparamagnetic relaxation

Cited by in corpus (6)

• Thermal fluctuations of magnetic nanoparticles
• Interplay between surface anisotropy and dipolar interactions in an assembly of nanomagnets
• AC susceptibility of an assembly of nanomagnets: combined effects of surface anisotropy and dipolar interactions
• Effective anisotropy due to the surface of magnetic nanoparticles
• Spatial magnetization profile in spherical nanomagnets with surface anisotropy: Green's function approach
• Single-particle versus collective effects in assemblies of nanomagnets: screening