Magnetooptic response of nanostructures with 3D geometries

Abstract

In recent years, nonuniform magnetic textures have gained substantial attention from the scientific community, due to their interesting properties and potential application in spintronic devices. One of the strategies for the realisation of such textures is through the manufacturing of complex-shape 3D nanostructures [1,2]. However, the complex geometry and magnetic configurations of such systems demand for the development of characterisation methods which combine high spatial resolution with high sensitivity. Magneto-optical Kerr effect (MOKE) magnetometry is a standard magnetic characterisation technique, usually employed to investigate both nanostructures and thin film planar systems [3]. Recently, the dark-field MOKE (DF-MOKE) method has been developed in our group, to characterise magnetic properties of 3D nanostructures [4]. In DF-MOKE, the magneto-optical signals coming from different planes of a 3D nano-geometry are detected independently, exploiting the specular reflection at different angles from each plane. In this contribution, the DF-MOKE characterisation of 3D magnetic nanostructures with different geometries and materials will be presented. The nanostructures under investigation were prepared using FEBID-based direct 3D nano-printing using our f3ast software [5]. Among the structures characterised, we will discuss results in ramp-shaped domain wall conduits, and in double-helix nano-geometries exhibiting complex 3D spin textures. We will discuss the sensitivity of the method and present its application to not only measure signal reflected from a single nanostructure, but also from sets of nanostructures close to each other. These results highlight the potential of DF-MOKE for advanced investigation of 3D magnetic nanostructures, including single nano-objects and arrays.