Effects of B and N modified interface and applied bias on the magnetoresistance in Fe/MgO/Fe magnetic tunnel junctions

The Fe/MgO/Fe magnetic tunnel junction with B and N modified interfaces has been studied based on the first-principle density function theory method. For junctions with thin ( five layers) and thick (ten layers) MgO barriers, positive and negative tunneling magnetic resistance (TMR) ratios are obtained as a function of the interface structure under finite bias voltage. The junctions with B modified interface have Delta 1 channel conductance perfectly preserved. But the spin filtering effect is reduced and thus very low TMR value is resulted. N modified interface has obvious influence to the interfacial state and drastically changes the bias dependence of the TMR output, which is promising for multifunction spintronic device applications with high TMR output and optimized bias dependence. Also, the formation energy of N insertion at the interface is lower than that of B. It will be very effective to prevent B staying at the interface with N insertion. Published by AIP Publishing.