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

Abstract

We have fabricated single crystal chromium dioxide $\left({\mathrm{CrO}}_2\right)$ films using chemical vapor deposition with chromyl chloride $\left({\mathrm{CrO}}_2{\mathrm{Cl}}_2\right)$ 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 ${\mathrm{CrO}}_3$ solid precursor. The process using the liquid precursor is superior to other existing techniques for the preparation of single crystal single- and multilayers containing ${\mathrm{CrO}}_2,$ especially the structure of magnetic tunnel junctions.