  Superconductor-ferromagnet (S-F) hybrids based on half-metallic ferromagnets,
such as CrO2, are excellent candidates for superconducting spintronic
applications. This is primarily due to their fully spin polarized nature, which
produces significantly enhanced long-range triplet proximity effects.. However,
reliable production of CrO2-based Josephson junctions (JJs) is challenging,
mainly because of the difficulty to control the transparency of the S/F
interface. We have grown CrO2 nanowires by chemical vapor deposition on TiO2
substrates combined with selective area growth in trenches defined with
amorphous SiOx. This allows us to create lateral JJs, with the nanowire as the
weak link. We show that the nature of the growth is highly anisotropic, and
that the morphology of the CrO2 nanostructructures changes systematically
during the growth process, depending on the width of the trench. The detailed
growth study enables us to synthesise multifaceted and highly homogeneous CrO2
wires. These are utilized to fabricate JJs with high S/F interface
transparency, leading to large supercurrents. The well-defined geometry of the
device allows us to reliably estimate an exceptionally high critical current
density Jc = 10^9~Am^{-2} over a distance of 600~nm.
