Tunneling magnetoresistance of magnetic tunneling junction cell measured by conducting atomic force microscopy with ramping dc bias voltage rate

Magnetoresistance (MR) ratio in a magnetic tunneling junction cell with a structure of SiO₂ (20 nm)/Ta (5 nm)/Cu (20 nm)/Ta (5 nm)/NiFe (2 nm)/Cu (5 nm)/MnIr (10 nm)/CoFe (4 nm)/Al–O (1.5 nm)/CoFe (4 nm)/NiFe (20 nm)/Ta (50 nm) was measured by conducting atomic force microscopy to obtain I-V curves. Tunnel magnetoresistance was characterized from these nonlinear I-V curves. MR values of 33.9%, 30.5%, 30.3%, and 28% were obtained when applying magnetic fields of ±150 Oe at various dc bias voltage ramping rates. Several ramping rate values were 0.498, 4.65, 9.3, and 27.9 Hz, respectively.