Towards the geometrical control of the energy landscape of domain walls in Complex 3D nanostructures

Three-dimensional nanomagnetic systems, featuring novel and unconventional spin textures, offer an exciting platform to explore new magnetic phenomena, and also offer possibilities for the development of more efficient, capable and multifunctional technologies [1]. The three-dimensional geometry is predicted to have a significant influence on the dynamics of magnetic domain walls [2], soliton-like textures that form the basis of many spintronics devices proposed in recent years. Specifically, the introduction of curvature and torsion in these three-dimensional structures allows for direct control over properties such as anisotropy and chirality [3,4]. This way, new physics and functionalities can be realised, from three-dimensional chiral spin states [5] to ultrafast domain wall dynamics [6].

In this work, we demonstrate the capacity to engineer the energy landscape of Bloch point domain walls via the introduction of curvature in a 3D nanostructure. By a careful design of the geometry of the nanostructures, grown using focused electron beam induced deposition (FEBID) [7], we are able to stabilize Bloch point domain walls and introduce well defined pinning positions. To map the energy landscape of these domain walls, we employ soft X-ray magnetic microscopy and analyze XMCD-images after applying magnetic fields. This enables us to showcase our capability to control the strength of pinning by adjusting the curvature of the nanostructure. This insight into the control of the magnetic behaviour via complex geometries will help pave the way to the next generation of 3D spintronic devices.