Origin of ion bombardment induced Tb oxidation in Tb/Co multilayers

TL;DR

This study investigates how ion bombardment induces terbium oxidation in Tb/Co multilayers, revealing that defects created by different ion species facilitate oxygen diffusion, allowing control over magnetic properties.

Contribution

It demonstrates that ion-induced defects act as diffusion pathways for oxygen, enabling tailored oxidation and magnetic property modification in Tb/Co multilayers.

Findings

Ion bombardment creates defects that facilitate oxygen diffusion.

Different ion species and fluences can tailor the film composition.

Selective oxidation reduces magnetically-active Tb.

Abstract

Ion bombardment is currently an active area of research for patterning rare earth/transition metal ferrimagnetic thin films because the magnetic properties are extremely sensitive to changes in the constituent sublattices. It has previously been shown that ion bombardment can be used to deliberately reduce the contribution of the rare earth sublattice in rare earth/transition metal ferrimagnets by selective oxidation. However, the exact mechanism by which oxidation occurs remains an outstanding question. We show that the defects introduced by ion bombardment of Tb/Co multilayers using different ion species with projected range (i.e., 10 keV He + , 15 keV O + , and 30 keV Ga +) create easy diffusion paths for oxygen to penetrate the system. The choice of ion species and fluence enables the effective composition of the films to be tailored by reducing the amount of magnetically-active Tb.