Bulklike behavior of magnetoelasticity in epitaxial Fe1-xGax thin films

Bulk Fe1-xGax alloys present a strong sensitivity of the magnetostrictive properties with Ga content with maximum magnetostriction near x=0.19. Here, we present magnetoelastic coefficients measured by the cantilever method on Fe1-xGax thin films grown by molecular beam epitaxy on GaAs(001). We find that Ga-dependent magnetoelastic coefficients in nanometer thin films are comparable in magnitude to the respective bulk values. Moreover, we compare thin films with a tetragonal structure due to a slightly preferential alignment of Ga pairs along the growth direction with and a cubic structure. It turns out that magnetoelastic coefficients are unaffected by a preferential alignment of Ga pairs along the growth direction.Fil: Barturen, Mariana. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Universidad Argentina de la Empresa; Argentina. Université Pierre et Marie Curie; Francia. Centre National de la Recherche Scientifique; Francia. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Sander, D.. Max Planck Institute For Microstructure Physics; AlemaniaFil: Milano, Julian. Centre National de la Recherche Scientifique; Francia. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche | Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche; ArgentinaFil: Premper, J.. Max Planck Institute For Microstructure Physics; AlemaniaFil: Helman, Christian. Comisión Nacional de Energía Atómica; ArgentinaFil: Eddrief, M.. Universite de Paris VI. Institut des Nanosciences de Paris; FranciaFil: Kirschner, J.. Max Planck Institute For Microstructure Physics; AlemaniaFil: Marangolo, M.. Universite de Paris VI. Institut des Nanosciences de Paris; Franci

Surface stress and lattice dynamics in oxide ultrathin films

The lattice misfit between the substrate and an epitaxial film leads in general to static forces, which define the interface stress, and dynamic responses that modify the thin-film lattice dynamics. Although these are both fundamental concepts that are important for film growth and thin-film properties, they have not been investigated in a combined way so far. Therefore, herein, surface stress experiments in combination with surface phonon studies for three different, cubic oxide ultrathin film systems are reviewed. Within the class of binary oxides, NiO(001) grown on Ag(001) is chosen, which exhibits a -2.2% lattice mismatch, and BaO(001) on Pt(001), a system with a negligible lattice mismatch. For the ternary oxides, perovskite thin films of BaTiO3 grown epitaxially on Pt(001) with a lattice mismatch of -2.3% are focused upon. The surface stress experiments are conducted with an optical two-beam curvature technique under in situ growth conditions. Surface and thin-film phonons are determined by high-resolution electron energy loss spectroscopy. Surface stress and lattice dynamics are discussed in the range from the oxide monolayer to thin films of about 20 unit cell in thickness

Large Rashba spin splitting of a metallic surface-state band on a semiconductor surface

The generation of spin-polarized electrons at room temperature is an essential step in developing semiconductor spintronic applications. To this end, we studied the electronic states of a Ge(111) surface, covered with a lead monolayer at a fractional coverage of 4/3, by angle-resolved photoelectron spectroscopy (ARPES), spin-resolved ARPES and first-principles electronic structure calculation. We demonstrate that a metallic surface-state band with a dominant Pb 6p character exhibits a large Rashba spin splitting of 200 meV and an effective mass of 0.028 me at the Fermi level. This finding provides a material basis for the novel field of spin transport/accumulation on semiconductor surfaces. Charge density analysis of the surface state indicated that large spin splitting was induced by asymmetric charge distribution in close proximity to the nuclei of Pb atoms