Large spin-filtering effects in epitaxial graphene-based spin valves is found to be strongly enhanced in
when chemical vapor deposited multilayer graphene is combined with a high quality epitaxial Ni(111) ferromagnetic spin source. Spin-transport measurements in these structures give rise to large negative tunnel magneto-resistance TMR = −160%, pointing to a particularly large spin polarization for the Ni(111)/Gr interface PNi/Gr, evaluated up to −98%. In collaboration with CNRS-Thales, Dr. Simon Dubois (in the group of Prof. J.-C. Charlier - IMCN/MODL) discussed an emerging physical picture of graphene−ferromagnet systems, sustained both by experimental data and ab initio calculations, intimately combining efficient spin filtering effects arising (i)
from the bulk band structure of the graphene layers purifying the extracted spin direction, (ii) from the hybridization effects modulating the amplitude of spin polarized scattering states over the first few graphene layers at the interface, and (iii) from the epitaxial interfacial matching of the graphene layers with the spin-polarized Ni surface selecting well-defined spin polarized channels. Importantly, these main spin selection effects are shown to be either cooperating or competing, explaining why these transport results were not observed before. Overall, this study unveils a path to harness the full potential of low Resitance.Area graphene interfaces in efficient spin-based devices.
Ref : Almost perfect spin filtering in graphene-based magnetic tunnel junctions
V. Zatko, S.M.-M. Dubois, F. Godel, M. Galbiati, J. Peiro, A. Sander, C. Carrétéro, A. Vecchiola,
S. Collin, K. Bouzehouane, B. Servet, F. Petroff, J.-C. Charlier, M.-B. Martin, B. Dlubak, and P. Seneor
ACS Nano 16, 14007-14016 (2022) doi: 10.1021/acsnano.2c03625