Junction size effect on switching current and thermal stability in CoFeB/MgO perpendicular magnetic tunnel junctions

Junction size dependence of critical current (I-C0) for spin transfer torque switching and thermal stability factor (E/k(B)T) was examined in CoFeB/MgO perpendicular magnetic tunnel junctions (p-MTJs). The I-C0 increased with increasing recording layer area (S-rec). On the other hand, the E/k(B)T showed almost constant values even though the S-rec was increased from similar to 1500 nm(2) (44 nm phi) to similar to 5000 nm(2) (76 nm phi). Both I-C0 and E/k(B)T behavior can be explained with assuming that the nucleation type magnetization reversal takes place in CoFeB/MgO p-MTJs. (C) 2011 American Institute of Physics. [doi:10.1063/1.3617429]