Resonant tunneling can lead to inverse tunnel magnetoresistance when impurity levels rather than direct tunneling dominate the transport process. We fabricated hybrid magnetic tunnel junctions of CoFe/LiF/EuS/Ti, with an epitaxial LiF energy barrier joined with a polycrystalline EuS spin-filter bar-rier. Due to the water solubility of LiF, the devices were fully packaged in situ. The devices showed sizeable positive TMR up to 16% at low bias voltages but clearly inverted TMR at higher bias voltages. The TMR inversion depends sensitively on the thickness of LiF, and the tendency of inversion disap-pears when LiF gets thick enough and recovers its intrinsic properties.
@article{arxiv.1604.08185,
title = {Resonant TMR inversion in LiF/EuS based spin-filter tunnel junctions},
author = {Fen Liu and Yihang Yang and Qian Xue and Zhiwei Gao and Aixi Chen and Guo-Xing Miao},
journal= {arXiv preprint arXiv:1604.08185},
year = {2016}
}