Abstract-A stereolithography-based manufacturing process for monolithic high aspect ratio components for mm-wave and sub-mm-wave applications is demonstrated. A 25 mm long straight waveguide and a diagonal horn antenna, both for the WR-3.4 band (220-330 GHz), are manufactured and characterized. The waveguide is found to exhibit transmission losses close to the theoretical minimum for Cu, and the performance of the diagonal antenna in terms of cross-polarization and directivity matches closely a metallic split-block reference antenna. These results confirm the high surface quality and mechanical accuracy of the employed 3D printing and plating techniques and thus validate the process for rapid manufacturing of monolithic components up to 330 GHz.

We present a combined theoretical and experimental study, investigating the origin of the enhanced non-adiabaticity of magnetic vortex cores. Scanning transmission X-ray microscopy is used to image the vortex core gyration dynamically to measure the non-adiabaticity with high precision, including a high confidence upper bound. Using both numerical computations and analytical derivations, we show that the large non-adiabaticity parameter observed experimentally can be explained by the presence of local spin currents arising from a texture-induced emergent Hall effect. This enhanced non-adiabaticity is only present in two-and three-dimensional magnetic textures such as vortices and skyrmions and absent in one-dimensional domain walls, in agreement with experimental observations.

We study the depinning of domain walls by pure diffusive spin currents in a nonlocal spin valve structure based on two ferromagnetic Permalloy elements with copper as the nonmagnetic spin conduit. The injected spin current is absorbed by the second Permalloy structure with a domain wall, and from the dependence of the wall depinning field on the spin current density we find an efficiency of 6×10{-14}  T/(A/m{2}), which is more than an order of magnitude larger than for conventional current induced domain-wall motion. Theoretically we find that this high efficiency arises from the surface torques exerted by the absorbed spin current that lead to efficient depinning.