Oscillation phenomenon of transition temperatures in Fe/V/Fe superlattice

Hossein Moradi 

Ferdowsi University of Mashhad, Azadi Square, Mashhad, Iran

Abstract

Many interesting physical properties of multilayer consisting of ferromagnetic films separated by nonmagnetic metallic spacers arise because of the coupling between the ferromagnetic layers. This coupling is mediated by the conduction electron in the spacer layers and oscillates with spacer thickness. The coupled system will have either ferromagnetic or staggered order depending on the sign of the interlayer coupling. The transition temperatures of these systems exhibit an oscillatory dependence on the spacer thickness and have a period of oscillation of half the period of the interlayer exchange coupling [1]. If there are fluctuations in the interlayer coupling caused by variations in the spacer thickness then each plane will experience a random magnetic field caused by combination of the strong correlation in the neighboring planes and the random exchange. This led to a theory, which predicted that the ordering temperature of multilayers thin films, may be less than the Curie temperature of an isolated plane [2].

In this paper, Curie temperature of an Ising plane in the presence of a random field is calculated in the mean field theory for a two dimensional lattice. The expressions for the susceptibility are used to obtain the transition temperature of coupled planes. It is shown that the results are fitted to experimental results and estimate the second AFM coupling peak in Fe/V/Fe superlattice. This indicates that the unusual oscillation behavior of the transition temperature as a function of spacer layer thickness is closely related to the interlayer exchange coupling in magnetic multilayers.

[1] K. Eftimova, et al. J. Magn. Magn. Mater. 240 (2002) 472-474.

[2] H. Moradi and G.A.Gehring, J. Magn. Magn. Mater. 251 (2002) 80-92.

 

Presentation: poster at E-MRS Fall Meeting 2005, Symposium F, by Hossein Moradi
See On-line Journal of E-MRS Fall Meeting 2005

Submitted: 2005-05-19 15:42
Revised:   2009-06-07 00:44