Magnetoresistance oscillations in double ferromagnetic tunnel junctions with layered ferromagnetic nanoparticles

Tunnel magnetoresistance in double tunnel junctions with layered ferromagnetic nanoparticles was investigated. The sample comprises two ferromagnetic electrodes (CoFe/Fe) separated by an Al/sub 2/O/sub 3/ insulating layer in which layered Co/sub 80/Pt/sub 20/ nanoparticles are embedded. The nanoparticles are ellipsoidal with an average diameter of 3.7 nm, and composes a well-defined layer. At 10 K, we observed magnetoresistance oscillation with respect to the bias voltage. The observed TMR oscillation, with a period of 1.6 mV, accompanied oscillations of the conductance. We consider that the conductance oscillation may originate from the single electron charging effect.