Magnetoresistance Governed by Fluctuations in Ultrasmall Ni/NiO/Co Junctions

Abstract
Electrodeposited Ni/NiO/Co heterostructures, with cross sections <0.01μm2, exhibit large steps of the magnetoresistance with ratios ranging from 4% to 50%. Two-level fluctuations of similar amplitude indicate that spin-dependent trapping and untrapping of electrons in the oxide barrier is the dominant effect. A hierarchical structure of the fluctuations is evidenced.