Magnetization reversal mechanism in La0.67Sr0.33MnO3 thin films on NdGaO3 substrates

The field angle dependence of the coercive field of La0.67Sr0.33MnO3 thin films grown epitaxially on NdGaO3 substrates with different crystallographic orientations was determined. All films show uniaxial anisotropy. The angle dependence of the coercivity is best described by a two-phase model, explaining the strong increase in the coercive field for increasing field angles, away from the easy axis direction, as well as the sharp decrease for angles close to the hard direction. This implies that magnetization reversal starts with the depinning of domain walls, analogous to the Kondorsky model. With increasing field the reversal in the domains is not abrupt, but is determined by the gradual displacement of the domain walls. These results are of significance for understanding and possibly engineering of the switching behavior of magnetic tunnel junctions

Anisotropic stress relief mechanism in epitaxial La0.67Sr0.33MnO3 films

We report an anisotropic misfit stress relief mechanism in thin La0.67Sr0.33MnO3 (LSMO) films coherently grown on NdGaO3(110) substrates. These results are uniquely related to the orthorhombicity of the LSMO. The x-ray diffraction measurements and quantitative simulations demonstrate that biaxial mismatch stress is relieved differently along in-plane directions perpendicular to each other: in the [1math0] direction stress is accommodated by decrease of the γ angle of the orthorhombic LSMO unit cell, while in the [001] direction stress is partially relieved by periodic lattice modulations

Rotation of the magnetic easy axis in La0.67Sr0.33MnO3 thin film on NdGaO3(112)

The in-plane magnetic anisotropy is studied for pseudocubic {011}pc oriented La0.67Sr0.33MnO3 (LSMO) thin film grown on orthorhombic NdGaO3(NGO)(112)o (the subindices “pc” and “o” indicate the pseudocubic and orthorhombic lattice structure, respectively). The direction of the in-plane remanent magnetization of LSMO thin films with different thicknesses is determined. With increasing film thickness the easy axes rotate and the anisotropy changes from uniaxial to biaxial. This is associated with the increasing symmetry of the LSMO with increasing thickness, starting with a monoclinic LSMO structure at the nonrectangular NGO(112)o surface unit cell of the substrate, developing into an orthorhombic structure at the top part of the thickest films

Low-temperature solution synthesis of chemically functional ferromagnetic FePtAu nanoparticles

Magnetic nanoparticles are of great scientific and technological interest. The application of ferromagnetic nanoparticles for high-density data storage has great potential, but energy efficient synthesis of uniform, isolated, and patternable nanoparticles that remain ferromagnetic at room temperature is not trivial. Here, we present a low-temperature solution synthesis method for FePtAu nanoparticles that addresses all those issues and therefore can be regarded as an important step toward applications. We show that the onset of the chemically ordered face-centered tetragonal (L10) phase is obtained for thermal annealing temperatures as low as 150 C. Large uniaxial magnetic anisotropy (107 erg/cm3) and a high long-range order parameter have been obtained. Our low-temperature solution annealing leaves the organic ligands intact, so that the possibility for postanneal monolayer formation and chemically assisted patterning on a surface is maintained

Optimized fabrication of high-quality La0.67Sr0.33MnO3 thin films considering all essential characteristics

In this paper, an overview of the fabrication and properties of high-quality La0.67Sr0.33MnO3 (LSMO) thin films is given. A high-quality LSMO film combines a smooth surface morphology with a large magnetization and a small residual resistivity, while avoiding precipitates and surface segregation. In the literature, typically only a few of these issues are adressed. We therefore present a thorough characterization of our films, which were grown by pulsed laser deposition. The films were characterized with reflection high energy electron diffraction, atomic force microscopy, x-ray diffraction, magnetization and transport measurements, x-ray photoelectron spectroscopy and scanning transmission electron microscopy. The films have a saturation magnetization of 4.0 µB/Mn, a Curie temperature of 350 K and a residual resistivity of 60 µΩ cm. These results indicate that high-quality films, combining both large magnetization and small residual resistivity, were realized. A comparison between different samples presented in the literature shows that focussing on a single property is insufficient for the optimization of the deposition process. For high-quality films, all properties have to be adressed. For LSMO devices, the thin-film quality is crucial for the device performance. Therefore, this research is important for the application of LSMO in devices

13C pulse-labeling assessment of the community structure of active fungi in the rhizosphere of a genetically starch-modified potato (Solanum tuberosum) cultivar and its parental isoline

The aim of this study was to gain understanding of the carbon flow from the roots of a genetically modified (GM) amylopectin-accumulating potato (Solanum tuberosum) cultivar and its parental isoline to the soil fungal community using stable isotope probing (SIP). • The microbes receiving 13C from the plant were assessed through RNA/phospholipid fatty acid analysis with stable isotope probing (PLFA-SIP) at three time-points (1, 5 and 12 d after the start of labeling). The communities of Ascomycota, Basidiomycota and Glomeromycota were analysed separately with RT-qPCR and terminal restriction fragment length polymorphism (T-RFLP). • Ascomycetes and glomeromycetes received carbon from the plant as early as 1 and 5 d after labeling, while basidiomycetes were slower in accumulating the labeled carbon. The rate of carbon allocation in the GM variety differed from that in its parental variety, thereby affecting soil fungal communities. • We conclude that both saprotrophic and mycorrhizal fungi rapidly metabolize organic substrates flowing from the root into the rhizosphere, that there are large differences in utilization of root-derived compounds at a lower phylogenetic level within investigated fungal phyla, and that active communities in the rhizosphere differ between the GM plant and its parental cultivar through effects of differential carbon flow from the plant.

13C pulse-labeling assessment of the community structure of active fungi in the rhizosphere of a genetically starch-modified potato (Solanum tuberosum) cultivar and its parental isoline

The aim of this study was to gain understanding of the carbon flow from the roots of a genetically modified (GM) amylopectin-accumulating potato (Solanum tuberosum) cultivar and its parental isoline to the soil fungal community using stable isotope probing (SIP). • The microbes receiving 13C from the plant were assessed through RNA/phospholipid fatty acid analysis with stable isotope probing (PLFA-SIP) at three time-points (1, 5 and 12 d after the start of labeling). The communities of Ascomycota, Basidiomycota and Glomeromycota were analysed separately with RT-qPCR and terminal restriction fragment length polymorphism (T-RFLP). • Ascomycetes and glomeromycetes received carbon from the plant as early as 1 and 5 d after labeling, while basidiomycetes were slower in accumulating the labeled carbon. The rate of carbon allocation in the GM variety differed from that in its parental variety, thereby affecting soil fungal communities. • We conclude that both saprotrophic and mycorrhizal fungi rapidly metabolize organic substrates flowing from the root into the rhizosphere, that there are large differences in utilization of root-derived compounds at a lower phylogenetic level within investigated fungal phyla, and that active communities in the rhizosphere differ between the GM plant and its parental cultivar through effects of differential carbon flow from the plant