Nanometers-thick self-organized Fe stripes: bridging the gap between surfaces and magnetic materials

We have fabricated 5nm-high Fe(110) stripes by self-organized (SO) growth on a slightly vicinal R(110)/Al2O3(11-20) surface, with R=Mo, W. Remanence, coercivity and domain patterns were observed at room temperature (RT). This contrasts with conventional SO epitaxial systems, that are superparamagnetic or even non-magnetic at RT due to their flatness. Our process should help to overcome superparamagnetism without compromise on the lateral size if SO systems are ever to be used in applications

Third type of domain wall in soft magnetic nanostrips

Magnetic domain walls (DWs) in nanostructures are low-dimensional objects that separate regions with uniform magnetisation. Since they can have different shapes and widths, DWs are an exciting playground for fundamental research, and became in the past years the subject of intense works, mainly focused on controlling, manipulating, and moving their internal magnetic configuration. In nanostrips with in-plane magnetisation, two DWs have been identified: in thin and narrow strips, transverse walls are energetically favored, while in thicker and wider strips vortex walls have lower energy. The associated phase diagram is now well established and often used to predict the low-energy magnetic configuration in a given magnetic nanostructure. However, besides the transverse and vortex walls, we find numerically that another type of wall exists in permalloy nanostrips. This third type of DW is characterised by a three-dimensional, flux closure micromagnetic structure with an unusual length and three internal degrees of freedom. Magnetic imaging on lithographically-patterned permalloy nanostrips confirms these predictions and shows that these DWs can be moved with an external magnetic field of about 1mT. An extended phase diagram describing the regions of stability of all known types of DWs in permalloy nanostrips is provided.Comment: 19 pages, 7 figure

Phase diagram of magnetic domain walls in spin valve nano-stripes

We investigate numerically the transverse versus vortex phase diagram of head-to-head domain walls in Co/Cu/Py spin valve nano-stripes (Py: Permalloy), in which the Co layer is mostly single domain while the Py layer hosts the domain wall. The range of stability of the transverse wall is shifted towards larger thickness compared to single Py layers, due to a magnetostatic screening effect between the two layers. An approached analytical scaling law is derived, which reproduces faithfully the phase diagram.Comment: 4 page

The dominant role of structure for solute transport in soil: experimental evidence and modelling of structure and transport in a field experiment

International audienceA classical transport experiment was performed in a field plot of 2.5 m2 using the dye tracer brilliant blue. The measured tracer distribution demonstrates the dominant role of the heterogeneous soil structure for solute transport. As with many other published experiments, this evidences the need of considering the macroscopic structure of soil to predict flow and transport. We combine three different approaches to represent the relevant structure of the specific situation of our experiment: i) direct measurement, ii) statistical description of heterogeneities and iii) a conceptual model of structure formation. The structure of soil layers was directly obtained from serial sections in the field. The sub-scale heterogeneity within the soil horizons was modelled through correlated random fields with estimated correlation lengths and anisotropy. Earthworm burrows played a dominant role at the transition between the upper soil horizon and the subsoil. A model based on percolation theory is introduced that mimics the geometry of earthworm burrow systems. The hydraulic material properties of the different structural units were obtained by direct measurements where available and by a best estimate otherwise. From the hydraulic structure, the 3-dimensional velocity field of water was calculated by solving Richards' Equation and solute transport was simulated. The simulated tracer distribution compares reasonably well with the experimental data. We conclude that a rough representation of the structure and a rough representation of the hydraulic properties might be sufficient to predict flow and transport, but both elements are definitely required

Tomographic Characterization of Three-Qubit Pure States with Only Two-Qubit Detectors

A tomographic process for three-qubit pure states using only pairwise detections is presented.Comment: 3 pages; revtex4; v2: the focus on tomography was emphasized and the experimental procedure detailed; v3: the text was improved in clarity, some mistakes were correcte

Verifying continuous-variable entanglement in finite spaces

Starting from arbitrary Hilbert spaces, we reduce the problem to verify entanglement of any bipartite quantum state to finite dimensional subspaces. Hence, entanglement is a finite dimensional property. A generalization for multipartite quantum states is also given.Comment: 4 page

Ammonia-Labile Bonds in High- and Low-Digestibility Strains of Switchgrass

Improvement in the forage quality of switchgrass (Panicum virgatum L.) through phenotypic selection for increased in vitro dry matter digestibility (IVDMD) has been demonstrated. This study tested the hypothesis that genetic improvement of fiber digestibility in switchgrass has been achieved by selection for a strain with a decreased quantity of ammonia-labile bonds. Tissue samples of a high-digestibility (high-IVDMD) and a low-digestibility strain (low-IVDMD) of switchgrass were ammoniated at rates of 0, 10, 20, and 40 g kg-1 dry matter. Fiber composition and in vitro rate and extent of neutral-detergent fiber (NDF) digestion were determined on control and ammoniated samples. The high-IVDMD strain had lower (P \u3c 0.05) concentrations of NDF and acid-detergent lignin (ADL) than the low-IVDMD strain. Lignin concentrations averaged 53 and 71 g kg-1 for the high- and low-IVDMD strains, respectively. The high-IVDMD strain had a greater (P \u3c 0.05) extent of NDF digestion when compared with the low strain; however, the rate of NDF digestion did not differ (P \u3e 0.05) between strains. Increased digestibility of the high-IVDMD strain was primarily attributed to increased cell-wall (NDF) digestibility. Ammoniation at 20 and 40 g kg-1 resulted in small decreases (P \u3c 0.05) in NDF concentrations when compared with the control; however, ammoniation had no effect on hemicellulose, cellulose, or ADL concentrations. Ammoniation increased (P \u3c 0.05) both the rate and extent of NDF digestion. Extent of NDF digestion averaged 0.395 for the control and 0.465, 0.498, and 0.493 for the 10, 20, and 40-g kg-1 treatments, respectively. Strain X ammoniation rate interaction was not significant for rate and extent of digestion, suggesting that genetic improvement in digestibility of switchgrass was not related to the number of ammonia-labile bonds

The Brunn-Minkowski inequality and a Minkowski problem for A-harmonic Green's function

Abstract In this article we study two classical problems in convex geometry associated to <m:mi mathvariant="script"

Do effective properties for unsaturated weakly layered porous media exist? An experimental study

International audienceIn a multi-step outflow experiment we found that a weak heterogeneity within a sand column prevents the estimated effective hydraulic parameters from being unique. We compared vertical water content profiles calculated from these parameters with profiles measured by x-ray attenuation. A layered material model based on x-ray data was able to reproduce the outflow curve and also the water content distribution inside the column. We also calculated effective parameters for the layered model turned upside down and obtained large differences to the set of values of the original sample

Double beta decay of 100Mo^{100}Mo: the deformed limit

The double beta decay of $^{100}Mo$ to the ground state and excited states of $^{100}Ru$ is analysed in the context of the pseudo SU(3) scheme. The results of this deformed limit are compared with the vibrational one based on the QRPA formalism. Consistency between the deformed limit and the experimental information is found for various $\beta\beta$ transitions, although, in this approximation some energies and B(E2) intensities cannot reproduced.Comment: 16 pages, revtex, no figures. Submmitted to Phys. Rev.