Jump of tunneling magnetoresistance in magnetic nanocontacts with mismatched cross section

Abstract

We have studied the influence of the transverse size of a magnetic tunnel nanojunction on the magnitude of the magnetoresistance. During modeling, the size of the right contact was fixed, while the size of the left one gradually changed until they coincided. We found a sharp drop in the tunneling magnetoresistance (TMR) in nanocontacts with mismatched cross section. This can be explained by the peculiarities of the spatial distribution of the electron density, which is different for majority and minority-spin states. Thus, our study indicates that the quantum size effect can also be a factor affecting the TMR ratio. Taking into account the observed effect can be important when designing the TMR-based nanodevices.