Cobalt Ferrite Films as described by third order perturbed Heisenberg Hamiltonian

P Samarasekara

doi:10.4038/josuk.v9i0.7839

Abstract

Magnetic properties of thick films of Cobalt ferrite have been investigated using third order perturbed modified Heisenberg Hamiltonian at different values of second and fourth order magnetic anisotropy. Thick films with up to 10,000 layers have been employed for this investigation. The magnetic energy versus number of layers, second and fourth order anisotropy have been plotted in order to find the magnetically easy and hard directions of cobalt ferrite films. Energy has minimum and maximum values at certain values of second and fourth order anisotropy values, indicating that that there are magnetically easy and hard directions. Energy shows the same type of variations with number of layers in the film. For the values considered in this manuscript, the easy direction of magnetization was found to be 153° with the normal line drawn to the film surface. However, the easy axis direction depends on the values of parameters used in simulation. Determination of easy directions of magnetic films is important in applications of magnetic memory devices. J. Sci. Univ. Kelaniya 9 (2014): 27-38

Highlights

Cobalt ferrite finds potential applications in, magnetic memory devices, microwave devices, hydrogen production devices (Rajendra et al, 2011), microelectromechanical system devices, stress sensors, actuators and magnetic nanobowls
The variation of total magnetic energy given in equation 11 was plotted against angle and as shown in figure 1
The energy is a maximum at that the film is difficult to magnetize along the hard directions at these values of According to the graph, there are many easy and hard directions for one particular value of

Summary

Introduction

Cobalt ferrite finds potential applications in, magnetic memory devices, microwave devices, hydrogen production devices (Rajendra et al, 2011), microelectromechanical system devices, stress sensors, actuators and magnetic nanobowls. The variation of magnetic energy with number of layers & stress induced anisotropy were plotted and the easy & hard directions were found using non-perturbed modified Heisenberg Hamiltonian (Samarasekara, 2007). The magnetic energy versus angle of spins & stress induced anisotropy were plotted and the easy & hard directions were calculated using the 2nd order perturbed modified Heisenberg Hamiltonian (Samarasekara et al, 2009, Samarasekara, 2010).

Results

Conclusion