Structural and magnetic properties of oxide films : A possible candidate for all-oxide TMR junctions?M. Eßeling, Y. Luo and K. Samwer
I. Physikalisches Institut, Universität Göttingen Tammannstr. 1, D-37077 Göttingen, Germany
received 13 February 2004; accepted in final form 9 August 2004
In search of a magnetic oxide, which is insensitive to oxygen at interfaces and thus appropriate as an electrode layer for tunneling junction applications, we prepared thin films of by reactive DC-magnetron sputtering technique and investigated the relation between structural and magnetic properties. The results suggest that the films consist of two disorded phases, a -rich and a -rich. It was found that the degree of film homogeneity and thus the magnetic nature depends on preparation conditions such as film thickness and deposition rate. A second magnetic phase with a high saturation field, which is present in thicker films, could therefore be reduced by decreasing the film thickness. Consequently, the thinnest film (10 ) is nearly single phased and exhibits an excellent uniaxial anisotropy with a coercive field of 16 along the easy axis. Additionally, thermomagnetic measurements were carried out to understand annealing-induced effects. A clear improvement with increased saturation magnetisation ( ) and decreased was observed, which can be attributed to structural relaxation and phase separation caused by annealing.
75.70.-i - Magnetic properties of thin films, surfaces, and interfaces.
75.50.-y - Studies of specific magnetic materials.
© EDP Sciences 2004