Symmetric magnetic tunnel junctions with amorphous soft magnetic materials as electrodes

Abstract Results concerning the influence of the additions of Ni and Ni–Si on the TMR response, saturating magnetic field and thermal stability of symmetric FeMn/FM/Al 2 O 3 /FM/FeMn MTJs, with FM=(Fe 0.58 Co 0.25 B 0.17 ) 100− x M x (M=Ni, Ni–Si), are presented. The magnetoresistance ratio for the symmetric Si/SiO 2 /Ta(5)/Ni 80 Fe 20 (5)/Fe 50 Mn 50 (8)/FeCoBNiSi(3.5)/Al 2 O 3 (1)/FeCoBNiSi(5)/Fe 50 Mn 50 (8)/Ta(5) MTJ structure was changed with about 9% in 20 G magnetic field, leading to a sensitivity of about 0.45%/G. This structure exhibits a field window of about 10 G and low values for the tunneling resistance of about 120 Ω and the thermal coefficient of resistance of about +60 ppm/°C.