Control of interlayer exchange coupling in Fe/Cr/Fe trilayers by ion beam irradiation

TL;DR

This study demonstrates that low-energy He ion beam irradiation can significantly alter the interlayer exchange coupling in Fe/Cr/Fe trilayers, either weakening or strengthening it depending on Cr spacer thickness, through atomic exchange effects.

Contribution

It reveals how moderate ion irradiation can controllably modify magnetic coupling in layered structures, introducing a new method for magnetic property tuning.

Findings

Coupling strength decreases with irradiation for thin Cr spacers.

Coupling strength increases for thicker Cr spacers after irradiation.

Atomic exchange events cause the observed changes in magnetic coupling.

Abstract

The manipulation of the antiferromagnetic interlayer coupling in the epitaxial Fe/Cr/Fe(001) trilayer system by moderate 5 keV He ion beam irradiation has been investigated experimentally. It is shown that even for irradiation with very low fluences (10^14 ions/cm^2) a drastic change in strength of the coupling appears. For thin Cr-spacers (below 0.6 - 0.7 nm) the coupling strength decreases with fluence, becoming ferromagnetic for fluences above (2x10^14 ions/cm^2). The effect is connected with the creation of magnetic bridges in the layered system due to atomic exchange events caused by the bombardment. For thicker Cr spacers (0.8 - 1.2 nm) an enhancement of the antiferromagnetic coupling strength is found. A possible explanation of the enhancement effect is given.