Soft X-ray Tomography of Curvilinear Spin Textures

The curvature degree of freedom is of fundamental importance to the formation and structural properties of magnetic spin textures (1, 2). Here, soft x-ray tomography reveals three-dimensional spin textures on curved scaffolds at nanoscale resolution. We present results from experiments at the MISTRAL beamline of the ALBA synchrotron on curved geometries(3). Samples consist of a Co/Pd multilayer film grown over curved surfaces of Cu nanowire networks. From a tilt series of hundreds of individual projections, the data are analyzed in three dimensions. The circularly polarized images contain both the structural curvature information and the magnetic contrast from domain walls (XMCD). In the nanowire network, a quantitative three-dimensional analysis finds the Gaussian curvature couples asymmetrically to the spin texture in the curved Co/Pd films. Saddle points at the crossings of nano-wires with negative Gaussian curvature promote the formation of domain walls, while regions of positive Gaussian curvature in the network inhibit the formation of domain walls. These results demonstrate the effectiveness of a metal-on-scaffold approach to fabricating and characterizing curvilinear spin textures, opening a flexible design space for future experiments.

1. Sheka, D. D. et al. Commun Phys 3 (2020)

2. Makarov, D. et al. Advanced Materials 34 (2022)

3. Sorrentino, A. et al. Journal of Synchrotron Radiation 22, 1112 (2015).