Perpendicular magnetic anisotropy induced by tetragonal distortion of FeCo alloy films grown on Pd(001)

We grew tetragonally distorted FexCo1-x alloy films on Pd(001). Theoretical first-principles calculations for such films predicted a high saturation magnetization and a high uniaxial magnetic anisotropy energy for specific values of the lattice distortion c/a and the alloy composition x. The magnetic anisotropy was investigated using the magneto-optical Kerr effect. An out-of-plane easy axis of magnetization was observed for Fe0.5Co0.5 films in the thickness range of 4 to 14 monolayers. The magnetic anisotropy energy induced by the tetragonal distortion is estimated to be almost 2 orders of magnitude larger than the value for bulk FeCo alloys. Using LEED Kikuchi patterns, a change of the easy axis of magnetization can be related to a decrease of the tetragonal distortion with thickness.     

Passively mode-locked Raman fiber laser with 100 GHz repetition rate

We experimentally demonstrate the operation of a passively mode-locked Raman fiber ring laser with an ultrahigh repetition rate of 100 GHz and up to 430 mW of average output power. This laser constitutes a simple wavelength versatile pulsed optical source. Stable mode locking is based on dissipative four-wave mixing with a single fiber Bragg grating acting as the mode-locking element.     

Medium modification of hadrons

I discuss pertinent aspects of the phase structure of strongly-interacting matter and their relation to the medium modifications of mesons. Special attention is paid to the critical endpoint in the phase diagram and the electromagnetic response in its vicinity.     

Expanded Prussian Blue Analogue Based on Octahedral {Nb<Subscript>6</Subscript>} Clusters and {K<Subscript>2</Subscript>} Dimers as Nodes

Abstract  The preparation, structures, and characterization of two new compounds containing octahedral niobium cyanochloride clusters as building units and (Et₄N)⁺ as cation are reported. The reaction between Nb₆Cl₁₄ · 8H₂O, KCN and (Et₄N)Cl led to the formation of (Et₄N)₄[Nb₆Cl₁₂(CN)₆] · 2.67H₂O (1) which crystallizes in triclinic P-1 space group (No. 2) with a = 12.552(2), b = 12.818(2), c = 12.919(2) ?, α = 105.157(3)°, β = 104.188(3)°, γ = 117.390(2)°, V = 1611.7(5) ?³ and Z = 1. 1 has a 2D hydrogen-bonded layer structure based on [Nb₆Cl₁₂(CN)₆]⁴⁻ units connected through hydrogen bonding between cyanide ligands and solvent water molecules. In the presence of large excess of K⁺ ions, similar reaction leads to formation of K₂(Et₄N)₂[Nb₆Cl₁₂(CN)₆] (2) which crystallizes in the tetragonal I4/m space group (No. 87) with a = b = 10.9597(3), c = 19.178(1) ?, V = 2303.6(2) ?³ and Z = 2. Its 3D structure is based on [Nb₆Cl₁₂]²⁺ and [K₂]²⁺ nodes bridged by cyanide ligands to form an expanded Prussian blue type framework with (Et₄N)⁺ acting as charge compensating ions. Index Abstract  An expanded Prussian blue type 3D framework based on hexanuclear {Nb₆} and dinuclear {K₂} units which are bridged by cyanide linker was synthesized and characterized. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Thin disk laser—Energy scaling

A time resolved numerical model of the interaction between pump absorption, excitation and amplified spontaneous emission (ASE) for the Thin Disk laser design was developed. The model accounts for the spectral distribution of the spontaneous emission, the spectral and spatial distribution of emission and absorption and the spectral and angular transmission of surfaces or coatings.     

Uniformization of {\mathcal {G}}-bundles

We show some of the conjectures of Pappas and Rapoport concerning the moduli stack Bun_G{{\rm Bun}_\mathcal {G}} of G{\mathcal {G}}-torsors on a curve C, where G{\mathcal {G}} is a semisimple Bruhat-Tits group scheme on C. In particular we prove the analog of the uniformization theorem of Drinfeld-Simpson in this setting. Furthermore we apply this to compute the connected components of these moduli stacks and to calculate the Picard group of Bun_G{{\rm Bun}_\mathcal {G}} in case G{\mathcal {G}} is simply connected.     

Investigation of chemical looping combustion of natural gas at 1 MWth scale

Chemical looping combustion (CLC) is an advanced oxyfuel process that enables CO₂ capture with low efficiency penalty. CLC of gaseous fuels has successfully been demonstrated in several pilots up to 150 kW_th. Numerous oxygen carriers have been tested regarding fuel conversion performance and lifetime. This work is a scale-up study of gaseous fuel CLC to MW_th scale. A Ca-Mn-based oxygen carrier has been developed and manufactured in ton-scale prior to the present test. Investigations were conducted in a 1 MW_th CLC unit that was adapted to utilize natural gas as fuel. Stable CLC conditions were reached during tests with Ca-Mn-based material, and the transition to operation with ilmenite was studied. The fuel conversion was in the range of 80%. During operation, 99% of the unburned methane was converted in the post oxidation chamber. The solids circulation rate and the lifetime of solids were determined by means of solids samples from the process, which were investigated in terms of attrition and degree of oxidation. The solids circulation rate was 17 tons h^?1  MW^?1 which is higher than in former tests but lower compared to other units. The most important limiting factors of the fuel conversion are the low solids inventory of the fuel reactor and the oxygen carrier to fuel ratio that corresponds to the solids circulation.