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

Junction size dependence of critical current (IC0) for spin transfer torque switching and thermal stability factor (E/kBT) was examined in CoFeB/MgO perpendicular magnetic tunnel junctions (p-MTJs). The IC0 increased with increasing recording layer area (Srec). On the other hand, the E/kBT showed almost constant values even though the Srec was increased from ∼1500 nm2 (44 nmφ) to ∼5000 nm2 (76 nmφ). Both IC0 and E/kBT behavior can be explained with assuming that the nucleation type magnetization reversal takes place in CoFeB/MgO p-MTJs.