Orientation of Easy Axis of Ferromagnetic Films as Explained by Third Order Perturbed Heisenberg Hamiltonian

Abstract

The third order perturbed Heisenberg Hamiltonian has been applied to explain the
magnetic easy axis orientation. Ferromagnetic CoPt/AlN multilayer thin films with
number of layers N=11, 16 and 21synthesized on fused quartz substrates using dc
magnetron sputtering technique have been employed as experimental data. According to
experimental research performed by some other researchers, easy axis of these fcc
structured ferromagnetic films is oriented in the plane of the film above one particular
temperature. Average value of out of plane spin component was plotted against
temperature in order to determine the spin reorientation temperature. The spin
reorientation temperature was highly sensitive to 2nd order magnetic anisotropy constant.
Keywords: Heisenberg Hamiltonian, easy axis, ferromagnetic, 3rd order perturbation