title: Large local Hall effect in pin-hole dominated multigraphene spin-valves.
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 AlO(x) 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.
authors.affiliation: Division of Superconductivity and Magnetism, Institut für Experimentelle Physik II, Universität Leipzig, Linnéstrasse 5, D-04103 Leipzig, Germany. muduli@physik.uni-leipzig.de
authors.forename: P K
authors.initials: PK
authors.lastname: Muduli
authors.forename: J
authors.initials: J
authors.lastname: Barzola-Quiquia
authors.forename: S
authors.initials: S
authors.lastname: Dusari
authors.forename: A
authors.initials: A
authors.lastname: Ballestar
authors.forename: F
authors.initials: F
authors.lastname: Bern
authors.forename: W
authors.initials: W
authors.lastname: Böhlmann
authors.forename: P
authors.initials: P
authors.lastname: Esquinazi