0000000000563512
AUTHOR
N. Auth
Spin polarization of magnetoresistive materials by point contact spectroscopy
In the strive to find a straightforward method for determining the spin polarization, the analysis of the Andreev reflection process in point contact junctions has attracted much interest. However, the prerequisite for anevaluation of the transport spin polarization in this scheme is the existence of elastic (ballistic or diffusive) transport, which cannot be assumed a priori. We therefore also include inelastic processes in our analysis and exemplify that thermal effects can have a significant effect on data evaluation. As ferromagnetic samples with a predicted half metallic behavior and comparably low conductivity we used thin films of the double perovskite Sr 2 FeMoO 6 and bulk material …
Pulsed laser deposition of Sr2FeMoO6 thin films
Abstract The effect of various deposition conditions and after-growth protocols on the magnetic and transport properties of Sr 2 FeMoO 6 films has been explored. It is found that the saturation magnetization and the magnetoresistance (MR) are dominated by the degree of cationic order, and the strain effects are clearly evidenced in a lower T C . The after-growth annealing of the films and the deposition of a buffer layer has been found to relax the film strains. This translates into a clear increase of the measured low-field magnetoresistance ratios.
Thin epitaxial films of the Heusler compound
Abstract We prepared thin films of the Heusler compound Co 2 Cr 0.6 Fe 0.4 Al with the B2 structure on a-plane (1 1 2 ¯ 0) Al 2 O 3 by sputtering. Films grown at high temperatures ( T ⩾ 600 ∘ C ) on Al 2 O 3 are fully epitaxial with the (1 1 0) and (1 1 ¯ 0) planes of the film parallel to the (1 1 2 ¯ 0) and (0 0 0 1) planes of the substrate, respectively. These epitaxial films possess a higher surface roughness than films grown at room temperature. The films show nearly rectangular hysteresis loops with coercive fields of the order of 10 mT. Magnetooptical Kerr measurements show an in-plane anisotropy of the magnetization with the easy axis in { 0 0 1 } direction. Hall measurements s…
Crystal structure and magnetism of the double perovskites A2FeReO6 (A=Ca, Sr, Ba)
Abstract We synthesized a series of double perovskites A 2 FeReO 6 (A=Ca, Sr, Ba) with Curie temperatures above room-temperature. Neutron and X-ray diffraction analysis have been performed in order to determine the structural and (local) magnetic properties of these materials. While Ba 2 FeReO 6 stays cubic over the whole temperature range we examined, the Sr-compound shows a tetragonal distortion of the perovskite structure which does not completely vanish up to about 520 K far above T C . Ca 2 FeReO 6 has a monoclinic unit cell at high temperatures. Below 400 K a phase separation in two monoclinic phases with identical cell volume is observed in neutron scattering.