Figure 3
From: Giant magnetoresistance in lateral metallic nanostructures for spintronic applications
(a) SEM image of a multi-terminal device. The four CoFe magnetic electrodes are connected to an Al spacer. Each electrode has a distinct switching field. Different electrical setups for GMR measurements are possible, only one of them is presented here. The electrodes through which the current goes are used to create a spin accumulation. The two other electrodes are voltage probes, the voltage differences being due to both the Ohmic resistance and the spin accumulation. (b) Schematic illustration of the sample, enabling to distinguish more clearly the geometry of the ferromagnetic elements located beneath different non-magnetic parts (c) Two GMR measurements obtained in the measurement configuration of fig. (a) at 300 K. The red curve correspond to a field loop reaching saturation, while the blue one is a minor loop. Due to symmetries of the geometry (the contact areas and inter-electrodes distances are identical), the spin signal level are degenerated with respect to the magnetic states. As an example, the spin signal of level I corresponds actually to two magnetic configurations, as does the spin signal of level II. The four intermediate levels of signal (in the grey area) gather 12 magnetic states.
