Magnetic domains without domain walls: a unique effect of He+ ion bombardment in ferrimagnetic Co/Tb multilayers

TL;DR

This study demonstrates that keV He+ ion bombardment can create stable, multi-domain magnetic configurations without domain walls in ferrimagnetic Co/Tb multilayers, enabling smaller domain pattern engineering.

Contribution

It introduces a novel method of using light-ion bombardment to control magnetic domain structures without domain walls in ferrimagnetic multilayers.

Findings

Stable multi-domain configurations without domain walls achieved.

Ion bombardment influences the magnetic subsystems selectively.

Potential for engineering smaller magnetic domain patterns.

Abstract

We show that it is possible to engineer magnetic multi-domain configurations without domain walls in a prototypical rare earth/transition metal ferrimagnet using keV He+ ion bombardment. We additionally shown that these patterns display a particularly stable magnetic configuration due to a deep minimum in the free energy of the system which is caused by flux closure and the corresponding reduction of the magnetostatic part of the total free energy. This is possible because light-ion bombardment differently affects an elements relative contribution to the effective properties of the ferrimagnet. The impact of bombardment is stronger for rare earth elements. Therefore, it is possible to influence the relative contributions of the two magnetic subsystems in a controlled manner. The selection of material system and the use of light-ion bombardment open a route to engineer domain patterns in continuous magnetic films much smaller than what is currently considered possible.