DEPENDENCE OF THE MAGNETIC ANISOTROPY ON THE THICKNESS AND ANNEALING OF SPUTTER-DEPOSITED Ni-Mn-Ga THIN FILMS
|Mykola M. Krupa 3, Volodymyr A. Chernenko 3, Igor V. Lezhnenko 3, Makoto Ohtsuka 1, Galina V. Bondarkova 3, Yurii B. Skyrta 3, Manfred Kohl 2, Victor Lvov 4|
1. Tohoku University, Sendai, Japan
Magnetic characteristics of the martensitic Ni52Mn24Ga24 and Ni49.5Mn28Ga22.5 thin films prepared by the sputter-deposition on polycrystalline Al2O3 and glass substrates have been studied by ferromagnetic resonance and vibrating magnetometry.
As-deposited films turned out to be in paramagnetic state. Annealing at T=873 K or T=1273 K caused the films to be ferromagnetic with a weak in-plane anisotropy and strong, , perpendicular anisotropy, especially after annealing at T=1273 K. The magnetization of the films after annealing at 1273K is close to magnetization of pure nickel and decreases in two- three times for the films annealed at 873 K. The ferromagnetic resonance spectrum has a double structure and the width of the peaks becomes narrower with the increase of the temperature of annealing.
A perpendicular anisotropy takes place already in the annealed films of 0.1 microns thick. The width of the ferromagnetic resonance peak decreases with increasing film thickness while its position shifts toward the higher magnetic fields. It is found that the peak width for the annealed films on the glass substrate is narrower than that for the films on Al2O3 substrate. Moreover, the peak position for films on the Al2O3 is located at the lower magnetic fields than that for films on a glass. The aforementioned characteristics have been found to be dependent on the film composition as well.
Presentation: poster at E-MRS Fall Meeting 2005, Symposium C, by Mykola M. Krupa
See On-line Journal of E-MRS Fall Meeting 2005
Submitted: 2005-05-19 12:37 Revised: 2009-06-07 00:44