Near-complete spin polarization in atomically-smooth chromium-dioxide epitaxial films prepared using a CVD liquid precursor

We have fabricated single crystal chromium dioxide (CrO2) films using chemical vapor deposition with chromyl chloride (CrO2Cl2) as a liquid precursor. Their electrical and magnetic properties have been investigated. These films are atomically smooth with a rms roughness of less than 5 Å for 1000 Å thick films. We have obtained a spin polarization of P = 98.4%, as determined by the technique of point-contact Andreev reflection. Magnetization and resistivity measurements on these films are in good agreement with those measured on films made with the CrO3 solid precursor. The process using the liquid precursor is superior to other existing techniques for the preparation of single crystal single- and multilayers containing CrO2, especially the structure of magnetic tunnel junctions.