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Double barrier magnetic tunnel junction (DBMTJ) with layer structures Ta/Cu/Ni79Fe21/Ir22Mn78/Co75Fe25/Al -oxide/Ni79Fe21/Al-oxide/Co75Fe25/Ir22Mn78/ Py/Cu/Ta are deposited on Si/SiO2 wafer using magnetron sputtering. Tunneling magnetoresistance(TMR) ratio of 18.7% and 28.4%, resistance-area product RS of around 12.7 and 10.3 kΩμm2 and coercivity of 17.5 and 2.0 Oe at room temperature are obtained for the DBMTJ. Micromagnetic simulations for the dynamic domain structures under increasing DC current and the magnetic switching properties are done using the energy minimization method. The magnetocrystalline anisotropy constant K1=1.0×103 erg/cm3, spontaneous magnetization Ms=800 Oe, and exchange interaction constant A=1.0×10-6 erg/cm values for the free layer are taken from the parameters of Ni79Fe21 alloy. The simulations show that the dynamic butterfly-shaped domains and magnetization switching can occur in the free layer when a DC current passes through the DBMTJ on the order of 100 μA to 10 mA, under a DC bias voltage of 10-1000 mV. It decreases the magnetization in the free layer which results into the low TMR ratio observed in the DBMTJ.
Date of Conference: 4-8 April 2005