Synthesis, characterization and modeling of high quality ferromagnetic Crdoped AlN thin fi.pdfVIP

Synthesis, characterization and modeling of high quality ferromagnetic Cr-doped AlN thin films Stephen Y. Wu a), H.X. Liu a), Lin Gu b), R.K. Singh a), L. Budd a), M. van Schilfgaarde a), M.R. McCartney b , David J. Smith b)c), and N. Newman 1)a) a) Dept. of Chemical Materials Engineering, Arizona State University, Tempe, AZ 85287-6006 b) Center for Solid State Science, Arizona State University, Tempe, AZ 85287-1704 c) Dept. of Physics and Astronomy, Arizona State University, Tempe, AZ 85287-1504. 1) corresponding author We report a theoretical and experimental investigation of Cr-doped AlN. Density functional calculations predict that the isolated Cr t2 defect level in AlN is 1/3 full, falls approximately at midgap, and broadens into an impurity band for concentrations over 5%. Substitutional Al Cr N random alloys with 0.05 ≤ x ≤ 0.15 are predicted to have Curie 1-x x temperatures over 600 K. Experimentally, we have characterized and optimized the molecular beam epitaxy thin film growth process, and observed room temperature ferromagnetism with a coercive field, Hc, of 120 Oersted. The measured magnetic susceptibility indicates that over 33% of the Cr is magnetically active at room temperature and 40% at low temperature. 1 The combination of several discoveries in magnetic semiconductors has created a new 1 field of research that has been labeled spintronics. First, the observation of ferromagnetism in Mn-doped InAs and GaAs up to 100K has enhanced interest in finding and