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Seminarium MTPR - Prof. Piotr Kuświk

"Is it possible to create magnetic domains without domain walls?"

Date: October 5, 2022 , 13:00 – 14:00

Speaker: Prof. Piotr Kuświk
Affiliation: Institute of Molecular Physics, Polish Academy of Sciences, Poznań, Poland

It is well known that in ferromagnetic materials there are distinct regions called “magnetic domains” where the magnetization is oriented in the same direction. They arise spontaneously because energy decreases with elimination of stray-fields (magnetic fields flowing out of objects). The formation of magnetic domains is one frequent way by which nature cancels those stray-fields. However, due to the exchange interaction between neighboring spins, the magnetization direction cannot change abruptly at the border between domains. For this reason, there usually is a narrow strip of space between domains where the magnetization reorients smoothly: this region is called a “domain wall”. Therefore, the question arises of whether it is possible to create magnetic domains without domain walls in magnetic materials. In this presentation we will focus on ion bombardment patterning of ferrimagnetic/sperimagnetic rare earth (RE)-transition metal (TM) films (e.g. Tb/Co multilayers, GdCoFe alloy films), which enable local reduction of the contribution of RE sublattices to effective magnetic properties of a perpendicularly magnetized TM-RE film. This technique was used to fabricate a 2D artificial lattice of TM dominant areas embedded in the RE dominant matrix. In this pattern, we found a non-conventional magnetic configuration, in which adjacent magnetic domains with oppositely oriented effective magnetization exist without domain walls. This brings an interesting, new spin texture, which opens a way to fabricate domains on a much smaller scale than what is currently possible.

Chairman: Jarosław W. Kłos