Tunneling current-induced butterfly-shaped domains and magnetization switching in double-barrier magnetic tunnel junctions

Double barrier magnetic tunnel junction (DBMTJ) with layer structures Ta/Cu/Ni/sub 79/Fe/sub 21//Ir/sub 22/Mn/sub 78//Co/sub 75/Fe/sub 25//Al -oxide/Ni/sub 79/Fe/sub 21//Al-oxide/Co/sub 75/Fe/sub 25//Ir/sub 22/Mn/sub 78// Py/Cu/Ta are deposited on Si/SiO/sub 2/ 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 k/spl Omega//spl mu/m/sup 2/ 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 K/sub 1/=1.0/spl times/10/sup 3/ erg/cm/sup 3/, spontaneous magnetization M/sub s/=800 Oe, and exchange interaction constant A=1.0/spl times/10/sup -6/ erg/cm values for the free layer are taken from the parameters of Ni/sub 79/Fe/sub 21/ 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 /spl mu/A 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.