Temperature dependence of tunnel magnetoresistance and magnetization of IrMn based MTJ

The temperature dependence of spin-polarized tunnel magnetoresistance (TMR) is investigated between 30 K and 300 K for annealed junctions with the structure of Ta(5)/Cu(10)/Ta(5)/NiFe(2)/Cu(5)/IrMn(10)/ CoFe(2.5)/Al ₂O₃(1.5)/CoFe(2.5)/NiFe(t)/Ta(5), where t = 10 and 100 nm. For the junction (t = 100 nm) annealed in 270°C we were able to separate electron polarization spin-dependent and spin-independent contributions of TMR temperature dependence. The thermally spin waves excitation constants determined from temperature dependence of magnetization and polarization are comparable. For junction with t = 10 nm annealed in 300°C electron spin polarization conductance is small in comparison to high conductance via trapped states, which arises from defects and magnetic impurities diffusion.