60th Magnetic Materials Center Seminar
November 5, 2007, 15:30-
8th floor seminar room, Sengen

C. Y. You
So far, the tremendous TMR 500% at room temperature and 1010% at 5 K have been demonstrated in sputter-deposited CoFeB/MgO/CoFeB structures. But the behavior of B in the CoFeB electrode is less explained. Furthermore, the speculative conclusion of the B occupation within MgO barrier is much disputed taking account of ionic compound feature of MgO layer and valence balance. In this presentation, the B behavior will be discussed through a combination of investigations on Co40Fe40B20 ribbon and MgO/Co40Fe40B20 bilayer thin film.

Low TMR ratio in MTJ with structure MgO(sub)/MgO/CFAS/MgO/CFAS/CoFe/IrMn/Ru
R. Shan
MTJ with structure MgO(sub)/MgO/CFAS/MgO/CFAS/CoFe/IrMn/Ru annealed at 500 C in situ has nearly perfect L21 structure and also MgO(sub)/MgO/CFAS single layer has lower roughness than MgO(sub)/Cr/CFAS. However, CIPT and four-probe method measurement show that TMR ratio of this kind of MTJ is very low.

Microstructure and magnetic properties of NdFeB/Ta thin film
H. Takeshita
Nd2Fe14B-based thin films are candidate materials for recording media, micro-magnetic, micro-mechanical system (MEMS) etc. We have made an epitaxial Nd2Fe14B thin films on SiO2 substrate with Ta buffer layer. In this presentation, I would like to discuss the microstructure and magnetic properties of NdFeB/Ta thin films.