Publication Date:
2014-09-12
Description:
Magnetic properties of Co 40 Fe 40 B 20 (CoFeB) thin films sandwiched between Ta and MgAl 2 O 4 layers have been systematically studied. For as-grown state, Ta/CoFeB/MgAl 2 O 4 structures exhibit good perpendicular magnetic anisotropy (PMA) with interface anisotropy K i = 1.22 erg/cm 2 , which further increases to 1.30 erg/cm 2 after annealing, while MgAl 2 O 4 /CoFeB/Ta multilayer shows in-plane magnetic anisotropy and must be annealed in order to achieve PMA. For bottom CoFeB layer, the thickness window for PMA is from 0.6 to 1.0 nm, while that for top CoFeB layer is between 0.8 and 1.4 nm. Perpendicular magnetic tunnel junctions (p-MTJs) with a core structure of CoFeB/MgAl 2 O 4 /CoFeB have also been fabricated and tunneling magnetoresistance ratio of about 36% at room temperature and 63% at low temperature have been obtained. The intrinsic excitations in the p-MTJs have been identified by inelastic electron-tunneling spectroscopy.
Print ISSN:
0003-6951
Electronic ISSN:
1077-3118
Topics:
Physics
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