Magnetic Domain wall resistance in Half-metallic CrO2

The half-metallic CrO2 is experimentally confirmed to have the highest spin polarization of nearly 100%. It is an ideal system to study magnetic domain-wall resistance (DWR), which differs from the resistance (or resistivity) inside a single-domain. We design and prepare a CrO2 epitaxial nanostructure with an asymmetrical weak link to localize a single DW, using the techniques of chemical vapor deposition and selective-area growth. The weak link design provides us the capability to generate /annihilate a single DW by applying a moderate/strong reversing magnetic field. By contrasting the resistance between a single-domain state and a DW state under zero field, we obtain the domain wall resistance in half-metallic CrO2. Using the Levy-Zhang model of DWR and simulated domain wall contour, we further obtain the spin asymmetry ratio between resistivities in the two spin channels. The ratio, 4256 ± 388 at 5.0 K, is 2 to 3 orders larger than that of conventional ferromagnetic metals, attesting the half-metallicity of CrO2.