We show that elastic currents that take into account variations of the tunnel transmitivity with voltage and a large ratio of majority to minority spin densities of states of the s band, can account for the low voltage current anomalies observed in magnet-oxide-magnet junctions. The anomalies can be positive, negative or have a mixed form, depending of the position of the Fermi level in the s band, in agreement with observations. Magnon contribution is negligible small to account for the sharp drop of the magnetoresistance with the voltage bias.
@article{arxiv.cond-mat/0106123,
title = {Low Voltage I-V Characteristics in Magnetic Tunnel Junctions},
author = {G. G. Cabrera and N. Garcia},
journal= {arXiv preprint arXiv:cond-mat/0106123},
year = {2009}
}