Nanotechnology 24 (2013) 015703
P. K. Muduli, J. Barzola-Quiquia, S. Dusari, A. Ballestar, F. Bern,
W. Böhlmann, and P. Esquinazi
Abstract
We report local and non-local measurements in pin-hole dominated mesoscopic multigraphene
spin-valves. Local spin-valve measurements show spurious switching behavior in resistance
during magnetic field sweeping similar to the signal observed due to spin injection into
multigraphene. The switching behavior has been explained in terms of a local Hall effect due
to a thickness irregularity of the tunnel barrier. The local Hall effect appears due to a large
local magnetostatic field produced near the roughness in the AlOx tunnel barrier. In our
samples the resistance change due to the local Hall effect remains negligibly small above
75 K. A strong local Hall effect might hinder spin injection into multigraphene, resulting in no
spin signal in non-local measurements.
