Influence of surface anisotropy on the magnetization precessional switching in nanoparticles

Abstract

A study of surface anisotropy effects on the precessional switching of nanoparticles is presented. Spherical nanoparticles with uniaxial anisotropy in the bulk and radial anisotropy for spins on the boundary are considered. The multispin dynamics is found by using the Landau–Lifshitz equation with the effective field derived from a Heisenberg-type Hamiltonian. The expressions for critical magnetic fields that guarantee the precessional switching are derived analytically for the case of very strong exchange and weak surface anisotropy. These analytical results are also used to test the numerical approach that is applied to the general case of the problem. The distinct features of the precessional switching in nanoparticles are examined and their dependence on various parameters of the problem is discussed.