Spin-valve effects in point contacts to exchange biased Co40Fe40B20 films

TL;DR

This study investigates the magnetoresistance and nonlinear current-voltage behavior in point contacts between a normal metal and exchange-biased amorphous ferromagnetic Co40Fe40B20 films, revealing a surface spin valve effect influenced by film thickness.

Contribution

It demonstrates the existence of a surface spin valve effect in N-F point contacts and analyzes how exchange bias varies with film thickness, linking these effects to conventional spin-valve phenomena.

Findings

Surface spin valve effect observed in conductance.

Exchange bias inversely proportional to film thickness.

Magneto-transport effects similar to those in three-layer spin-valves.

Abstract

Nonlinear current-voltage characteristics and magnetoresistance of point contacts between a normal metal (N) and films of amorphous ferromagnet (F) Co40Fe40B20 of different thickness, exchange-biased by antiferromagnetic Mn80Ir20 are studied. A surface spin valve effect in the conductance of such F-N contacts is observed. The effect of exchange bias is found to be inversely proportional to the Co40Fe40B20 film thickness. This behavior as well as other magneto-transport effects we observe on single exchange-pinned ferromagnetic films are similar in nature to those found in conventional three-layer spin-valves.