Seminars Archive

Mon 5 Jun, at 14:30 - Seminar Room T2

Chris J. Palmstrøm

Chris J. Palmstrøm


Monday, June 5, 2000, 14:30
Seminar Room, ground floor, Building "T"
Sincrotrone Trieste, Basovizza I.D. required for external visitors
Epitaxial Ferromagnetic Metal/GaInAs(001) Heterostructures.

Chris J. Palmstrm

(Department of Chemical Engineering and Materials Science, University of Minnesota) ABSTRACT Ferromagnetic bcc FeXCo1-X and the Heusler alloy Ni2MnGa have been successfully grown on GaAs(001) by molecular beam epitaxy. In-situ reflection high energy diffraction and X-ray diffraction data show a cube-on-cube epitaxy with FeXCo1X(001)||GaAs(001) and Ni2MnGa(001)||GaAs(001). The Rutherford backscattering spectrometry channeling minimum yields of c~3.5% and ~6% for FexCo1-x and Ni2MnGa, respectively, suggests high quality single crystal films. In order to minimize interfacial reactions and to control the initial nucleation during the ferromagnetic film growth, we investigated the use of the epitaxial Sc1-xErXAs and NiGa as interlayers. Reflection high energy electron diffraction, X-ray diffraction and cross-sectional transmission electron microscopy indicate pseudomorphic Ni2MnGa single crystal ferromagnetic film growth on both interlayer surfaces. Vibrating sample magnetometry measurements show in-plane magnetization for both FexCo1-x and Ni2MnGa. Square hysteresis loops were obtained with the magnetic field applied along the easy axis of FexCo1-x. Magneto-Optic Kerr Effect measurements were used to study the switching mechanism of the magnetic moments. The magnetic properties of ferromagnet/semiconductor heterostructures depended upon surface symmetry, crystal structure and bonding of the interfacial layer. FexCo1-x films showed uniaxial anisotropy when grown directly on GaAs (001) and four-fold anisotropy when grown on a Sc1-xErxAs interlayer. Growth on vicinal substrates resulted in an additional step structure symmetry-induced magnetic anisotropy, which increased with angle of miscut. In this talk, the effects of the interlayer and vicinal surfaces on the growth mode and magnetic properties of the ferromagnet/GaAs heterostructures will be discussed.

Last Updated on Tuesday, 24 April 2012 15:21