Artificial Dense Lattices of Magnetic Skyrmions.

Maksim V Sapozhnikov,Yuri V Petrov,Victor L Mironov,Olga L Ermolaeva,Nikita S Gusev,Oleg G Udalov,Alexey G Temiryazev

doi:10.3390/ma13010099

Maksim V Sapozhnikov, Yuri V Petrov + Show 5 more

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https://doi.org/10.3390/ma13010099

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Abstract

Multilayer Co/Pt films with perpendicular magnetic anisotropy are irradiated by focused a He+ ion beam to locally reduce the anisotropy value. The irradiated spots with the diameters of 100 and 200 nm are arranged in square lattices with the periods of 200 and 300 nm. The formation of nonuniform magnetic states within the spots was observed by magnetic force microscopy methods. We use the concentric distribution of the irradiation fluence within the spot to obtain the radial modulation of the anisotropy constant. This allows us to induce magnetic skyrmions during magnetization reversal of the system. The skyrmions remained stable at zero external magnetic field at room temperature. Magnetization hysteresis loops of the samples were investigated by magnetooptical methods and the results are in good agreement with micromagnetic simulations.

Highlights

Soliton-like magnetization distributions in the magnetic materials with the easy-axis anisotropy are known since late 1970s [1,2,3,4,5]
In order to understand the process of the magnetization reversal and magnetic structure of the remnant state, we carried out micromagnetic simulations utilizing the Object Oriented
We have studied the magnetization reversal and apparent magnetic states in multilayer Co/Pt films nanopatterned by a He+ focused ion beam

Summary

Introduction

Soliton-like magnetization distributions (usually referred as “magnetic skyrmions”) in the magnetic materials with the easy-axis anisotropy are known since late 1970s [1,2,3,4,5]. The skyrmions demonstrate high mobility under an applied electric current [6], which can be exploited in spintronic memory and information processing devices. Since the DMI in these crystals is relatively weak, the skyrmions are stable within a narrow range of temperature and magnetic field only [9] This hinders the application of such topological objects. Ultrathin films of transitional ferromagnetic metal grown on a surface of heavy metal demonstrate strong interfacial DMI stabilizing skyrmions, even at room temperature [10,11]. These structures are presently the object of active study

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