Magnetoresistance of Fe/MgO/Fe magnetic tunnel junctions: Discrepancy between theory and experiment

The tunnel magnetoresistance (TMR) effect in magnetic tunnel junctions (MTJs) is the key to developing magnetoelectric devices. The MTJs with an epitaxial barrier, like MgO, appear more promising with respect to potential applications because of its high TMR ratio as predicted in experiment. However, there is always a controversy about the correct TMR ratio: in most of the theoretical investigations, the TMR ratios are found to be much higher than in their experimental counterparts. What are the possible reasons of this discrepancy? This presentation strives to seek an answer on the basis of recent works.