Point-contact Andreev reflection measurements reveal that amorphous Co x Fe80-x B20 (x=20, 40, and 60) alloys possess spin polarization of as much as 65%, much higher than the values of 43%-45% for Co and Fe. This accounts for the high magnetoresistance values in magnetic tunnel junctions incorporating amorphous CoFeB as the ferromagnetic electrodes. The crystallization of the amorphous alloys substantially reduces the spin polarization.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)