Spin Polarization ofCrO2at and across an Artificial Barrier

Abstract

We report a systematic study of the spin polarization of epitaxial ${\mathrm{CrO}}_2$ films at and across an interface using planar junctions with a superconducting counterelectrode. By chemical modification of the ${\mathrm{CrO}}_2$ surface before the deposition of the superconductor, junctions with a wide range of barrier strength were obtained. Analysis of the conductance data on these junctions, especially under Zeeman splitting of the superconducting density of states, yields consistent, close to full spin polarization for ${\mathrm{CrO}}_2$ regardless of the barrier strength.