79th Magnetic Materials Center Seminar
June 25, 2008, 9:00-
7th floor small seminar room, Sengen
Optimization of AlOx barrier in MTJ.
R. Shan
Without doubt, the performance of MTJ is decided by the spin polarization of FM electrode at interface, which can easily be calculated through Julliere's model when the TMR ratio of MTJ with FM/AlOx/FM structure was obtained, but not that of bulk material. However, the quality of AlOx barrier will also affect TMR ratio of MTJ and thus affect the calculation value of spin polarization. Therefore, good quality of barrier is a precondition to apply Julliere's model. In my work, optimization conditions of AlOx barrier were studied. TMR ratio of MTJ reached to maximum when Mg insert layer was employed before Al layer deposition. At same time, the TMR ratio of MTJ with Mg insert layer kept around 50% even oxidization time changed from 45 seconds to 150 seconds.

Granular FePt:(C,SiO2) films for Perpendicular recording.
A. Perumal
This aim of this presentation is to update the recent progress of our work on the successful preparation of granular type FePt:(C,SiO2) on thermally oxidized Si substrate with MgO underlayer. While the first part focuses on the results of FePt:C nanogranular films with the average grain size of about 5.5 nm with controllable magnetic properties, the second part covers the results on FePt:SiO2 films. The immediate/ distant future plan of the work would be also discussed at the end of the presentation.

Microstructure, magnetic and transport properties of Co ferrite thin film
Y. K. Takahashi
The highly spin polarized current source is necessary for the development of the high performance spintronics devices. Half metal is well known to produce the highly spin polarized current. The spin filtering device with ferromagnetic insulator can also produce it. The purpose of the research is to realize the spin filtering effect at RT. To do it, I choose the CoFe2O4 for the ferromagnetic insulator, because the Tc of the CoFe2O4 is much higher than RT. Up to now, there are some reports on the spin filtering effect of Co ferrite. However, large spin filtering effect at RT is not obtained yet. I think that the investigation of the relationship between magnetic properties, microstructure and transport properties is necessary to realize the spin filtering effect at RT. In this talk, I will present the microstructure, magnetic and transport properties of Co ferrite thin film.