| AVS 64th International Symposium & Exhibition | |
| Electronic Materials and Photonics Division | Monday Sessions |
| Session EM+MI+TF-MoM |
| Session: | Growth, Electronic, and Magnetic Properties of Heusler Compounds |
| Presenter: | Sean Harrington, University of California at Santa Barbara |
| Authors: | S.D. Harrington, University of California at Santa Barbara A.D. Rice, University of California at Santa Barbara T. Brown-Heft, University of California at Santa Barbara A.P. McFadden, University of California at Santa Barbara M. Pendharkar, University of California at Santa Barbara O. Mercan, Gebze Technical University, Turkey L. Çolakerol Arslan, Gebze Technical University, Turkey C.J. Palmstrøm, University of California at Santa Barbara |
| Correspondent: | Click to Email |
Recent predictions suggest the semiconducting half-Heusler compound, CoTiSb, exhibits half-metallicity when substitutionally alloyed with Fe. However, to date, few studies have examined the growth of high-quality single crystal thin films of Fe-alloyed CoTiSb. Here, we report the epitaxial growth of the substitutionally alloyed half-Heusler series CoTi1-xFexSb by molecular beam epitaxy and the influence of Fe on the structural, electronic, and magnetic properties. CoTi1-xFexSb epitaxial films are grown on InAlAs grown on InP (001) substrates for concentrations 0≤x≤1. The films are epitaxial and single crystalline, as measured by reflection high-energy electron diffraction and X‑ray diffraction. For films with higher Fe content, a lower growth temperature is necessary to minimize interfacial reactions. Using in-situ X-ray photoemission spectroscopy, only small changes in the valence band spectra from pure CoTiSb are detected. For films with x≥0.05, ferromagnetism is observed in SQUID magnetometry with a Curie temperature >400K. The saturation magnetization of the series increases linearly with Fe content as 3.4 μB/Fe atom. In comparison, there is a much smaller magnetic moment when the Fe is substituted on the Co site (Co1‑xFexTiSb) indicating a strong dependence of the magnetic moment with site occupancy. A cross over from both in-plane and out-of-plane magnetic moments to only in-plane occurs for higher concentrations of Fe. Ferromagnetic resonance indicates a transition from weak to strong interaction as Fe content is increased. Temperature dependent transport shows a gradual semiconductor to metal transition with thermally activated behavior for x≤0.3. Anomalous Hall effect and magneto resistance are investigated for the x=0.3 and x=0.5 films revealing large differences in the electronic scattering mechanisms and transport behavior depending on Fe content.