Magnetic properties and spin polarization of Ru doped half metallic CrO2

• Published in: Applied physics letters 2015-07, Vol.107 (1)
• Main Authors: West, Kevin G., Osofsky, Michael, Mazin, I. I., Dao, Nam N. H., Wolf, Stuart A., Lu, Jiwei
• Format: Article
• Language: English
• Subjects: Applied physics; Chromium oxides; Curie temperature; Dependence; Electrical resistivity; Electrons; Ferrimagnetism; First principles; Magnetic properties; Magnetic saturation; Magnetism; Physical vapor deposition; Polarization (spin alignment); Stability; Synthesis; Thin films
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4923274

Chromium dioxide (CrO2) is a half metal that is of interest for spintronic devices. It has not been synthesized through traditional physical vapor deposition (PVD) techniques because of its thermodynamic instability in low oxygen pressures. Epitaxial thin films of Ru doped tetragonal rutile CrO2 were synthesized by a PVD technique. The as-deposited RuxCr1−xO2 was ferrimagnetic with the saturation magnetization moment showing a strong dependence on the Ru concentration. Curie temperature as high as 241 K has been obtained for ∼23 at. % Ru. The Ru substitution increased the electrical conductivity by increasing the minority spin concentration. The spin polarization was found to be as high as 70% for 9 at. % Ru and decreased to ∼60% with Ru concentrations up to ∼44 at. %, which is determined by the Fermi velocities of the majority and minority spins. First principle calculations were performed to understand the effect of Ru content on the properties of CrO2. The PVD processes of Ru doped CrO2 could lead to the practical applications of the high spin polarization of CrO2 in spintronic devices.