Effect of interfacial nitrogen defects on tunnel magnetoresistance in an Fe/MgO/Fe magnetic tunnel junction

We investigated the effect of interfacial nitrogen (N) defects on tunnel magnetoresistance (TMR) in Fe/MgO/Fe magnetic tunnel junctions (MTJs) which are the basic building block of magnetoresistive random access memory. The N atoms are predicted to originate from the SiN covering for antioxidation. It was found from first-principles quantum-transport calculations that the N defects significantly worsen the TMR. This is particularly evident in the MTJ models with an additional N atom at the MgO/Fe interface, because a conduction channel appears in the antiparallel magnetization configuration due to the N defects. The TMR is directly related to the read error rate of data and the scaling of the memory cell. Therefore, the prevention of nitrogen contamination during the manufacturing processes is a prerequisite for maintaining high performance.