Sample fabrication effects in exchange bias systems

Abstract

In exchange coupled granular films the reversal process is usually that of reverse domain nucleation and domain wall propagation. Local effects such as surface irregularities can affect the nucleation process significantly. We describe the effects of nucleation arising from both sample shape effects and the process used to cut the samples. Cutting techniques such as the use of ultrasonic cutters lead to a large increase in nucleation, which distorts the hysteresis loop. Deposition through masks causes shadowing effects at the edges that also distort the loops. Cutting with a diamond scribe appears to give the best outcome. Implications for devices based on nanoelements are discussed.