High-Quality CrO 2 Nanowires for Dissipation-less Spintronics

摘要

Superconductor-ferromagnet (S-F) hybrids based on half-metallic ferromagnets, such as CrO 2 , are ideal candidates for superconducting spintronic applications. This is primarily due to the fully spin-polarized nature of CrO 2 , which produces enhanced long-range triplet proximity effects. However, reliable production of CrO 2 -based Josephson junctions (JJs) has proved to be extremely challenging because of a poorly controlled interface transparency and an incomplete knowledge of the local magnetization of the CrO 2 films. To address these issues, we use a bottom-up approach to grow CrO 2 nanowires on prepatterned substrates via chemical-vapor deposition. A comprehensive study of the growth mechanism enables us to reliably synthesize faceted, homogeneous CrO 2 wires with a well-defined magnetization state. Combining these high-quality wires with a superconductor produces JJs with a high interface transparency, leading to exceptionally large 100% spin-polarized supercurrents, with critical current densities exceeding 10 9 Am ? 2 over distances as long as 600?nm. These CrO 2 -nanowire-based JJs thus provide a realistic route to creating a scalable device platform for dissipation-less spintronics.