We studied metastable α-FeGe2, a novel layered tetragonal material, embedded as a spacer layer in spin valve structures with ferromagnetic Fe3Si and Co2FeSi electrodes. For both types of electrodes, spin valve operation is demonstrated with a metallic transport behavior of the α-FeGe2 spacer layer. The spin valve signals are found to increase both with temperature and spacer thickness, which is discussed in terms of a decreasing magnetic coupling strength between the ferromagnetic bottom and top electrodes. The temperature-dependent resistances of the spin valve structures exhibit characteristic features, which are explained by ferromagnetic phase transitions between 55 and 110~K. The metallic transport characteristics as well as the low-temperature ferromagnetism are found to be consistent with the results of first-principles calculations.
@article{arxiv.2010.04453,
title = {Electronic and magnetic properties of $\alpha$-FeGe$_2$ films embedded in vertical spin valve devices},
author = {Dietmar Czubak and Samuel Gaucher and Lars Oppermann and Jens Herfort and Klaus Zollner and Jaroslav Fabian and Holger T. Grahn and Manfred Ramsteiner},
journal= {arXiv preprint arXiv:2010.04453},
year = {2020}
}