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M n 2 Au is a bimetallic antiferromagnetic with an extraordinarily high Néel temperature of 1600 K. M n 2 Au has also been found to demonstrate Néel-order spin–orbit torque, allowing for electrical switching of the antiferromagnetic Néel vector. This has led to much interest in this material for spintronic applications. Here, we detail the growth of high quality M n 2 Au (110) thin films. The films were grown on a high quality Pt (111) buffer layer, which was grown on an A l 2 O 3 (0001) substrate. The M n 2 Au films have excellent crystalline quality as demonstrated by x-ray diffraction, x-ray reflection, and reflection high energy electron diffraction measurements. The M n 2 Au (110) films are found to grow with three equivalent in-plane rotation domains, caused by the Pt/ A l 2 O 3 substrate. [ABSTRACT FROM AUTHOR]

The search for multiferroic order in a single phase of bismuth pyrochlore has been unsuccessful so far. In this direction, our study unveiled the capability of a biphase of bismuth pyrochlore and spinel in hosting a multiferroic order at room temperature. A complex oxide biphase of cubic pyrochlore and cubic spinel crystals acquired in the Bi2O3-Nb2O5-2MnCO3-Fe2O3 system revealed the crystals of a spinel phase (Fe1.59(3)Mn1.39(3)O4.26(7)) intergrown in the dense pyrochlore (Bi1.35(1)Fe0.64(1)Nb1.26(1)Mn0.75(1)O6.39(5)) matrix. The average composition of the components of the investigated biphase was determined using an electron probe microanalyzer (EPMA). The structural features indicated the presence of large ionic displacements within the cubic pyrochlore phase as seen from the appearance of 442 reflection in the X-ray diffraction pattern and infrared active mode at ∼64 cm−1 in the Raman spectrum recorded at room temperature. The pyrochlore single-phase composition (Bi1.35(1)Fe0.64(1)Nb1.26(1)Mn0.75(1)O6.39(5)), as suggested from a thorough EPMA microstructural analysis, exhibited broad dielectric relaxation and an overall paramagnetic behavior. The observation of disordered superparamagnetism as well as dielectric relaxation in the biphase conformed to that of a relaxorlike multiferroic behavior at room temperature. Moreover, self-biased magnetoelectric voltage coefficients of 0.60 mV/cm Oe at 100 Hz and 5.54 mV/cm Oe at 1 kHz were detected between magnetization and electric polarization at room temperature. Therefore, the composite of such a pyrochlore and spinel with an inherent property of strong spin–orbit and spin–lattice coupling will be interesting from theoretical and experimental point of view in the arena of magnetoelectrics. [ABSTRACT FROM AUTHOR]

X-ray reflectivity is a promising technique for characterizing buried layers and interfaces in ultrathin films because of its ability to probe the electron density profile along the depth in a nondestructive manner. While routine X-ray reflectivity assumes the in-plane uniformity of the sample to be measured, it is also quite important to see buried inhomogeneous/patterned layers and interfaces. The present paper describes the addition of spatial resolution and imaging capability to an X-ray reflectivity technique to visualize surfaces and buried interfaces. To visualize quite wide viewing area size quickly, the image reconstruction scheme has been employed instead of the scanning of microbeam. Though the mathematics is quite close to X-ray computer tomography, the technique gives the image contrast caused by the difference in reflectivity at each in-plane point in the thin film sample. By choosing a grazing angle, the image gives inhomogeneity of X-ray reflectivity at the specific wavevector transfer. With a collimated monochromatic synchrotron X-ray beam of 0.05 mm (H) × 8 mm (V), the intensity profiles of X-ray reflection projections have been taken at many different in-plane rotation angles, from 0° to 180°. We have succeeded in visualizing buried layers and interfaces of the 8 mm dia area with the spatial resolution of better than 20 μm. Because of the brilliance of synchrotron radiation, the typical measuring time is shorter than 1 min. Three analytical cases have been discussed: (i) imaging of a buried layer and an interface covered by a protection layer, (ii) distinguishing different local parts of different thicknesses in an ultrathin film, and (iii) selective imaging of a specific metal in the thin film form. [ABSTRACT FROM AUTHOR]

The highly coherent and tightly focused x-ray beams produced by hard x-ray light sources enable the nanoscale characterization of the structure of electronic materials but are accompanied by significant challenges in the interpretation of diffraction and scattering patterns. X-ray nanobeams exhibit optical coherence combined with a large angular divergence introduced by the x-ray focusing optics. The scattering of nanofocused x-ray beams from intricate semiconductor heterostructures produces a complex distribution of scattered intensity. We report here an extension of coherent x-ray optical simulations of convergent x-ray beam diffraction patterns to arbitrary x-ray incident angles to allow the nanobeam diffraction patterns of complex heterostructures to be simulated faithfully. These methods are used to extract the misorientation of lattice planes and the strain of individual layers from synchrotron x-ray nanobeam diffraction patterns of Si/SiGe heterostructures relevant to applications in quantum electronic devices. The systematic interpretation of nanobeam diffraction patterns from semiconductor heterostructures presents a new opportunity in characterizing and ultimately designing electronic materials. [ABSTRACT FROM AUTHOR]

We study the effect of low-temperature post growth annealing on the Fe layer in an epitaxial Fe/GaAs(001) heterojunction. High resolution X-ray diffraction and X-ray reflectivity were used to probe the Fe layer before and after annealing. No change in morphological features like annealing induced intermixing and thickness variation of the Fe layer are observed. However, annealing leads to increase in the compressive strain and improves isotropy of the ferromagnetic layer as revealed by measuring both lateral and out-of-plane lattice components. [ABSTRACT FROM AUTHOR]

Microstructure and composition analysis of periodic multilayer structure consisting of a low electron density contrast (EDC) material combination by grazing incidence hard X-ray reflectivity (GIXR), resonant soft X-ray reflectivity (RSXR), and transmission electron microscopy (TEM) are presented. Measurements of reflectivity at different energies allow combining the sensitivity of GIXR data to microstructural parameters like layer thicknesses and interfacing roughness, with the layer composition sensitivity of RSXR. These aspects are shown with an example of 10-period C/B4C multilayer. TEM observation reveals that interfaces C on B4C and B4C on C are symmetric. Although GIXR provides limited structural information when EDC between layers is low, measurements using a scattering technique like GIXR with a microscopic technique like TEM improve the microstructural information of low EDC combination. The optical constants of buried layers have been derived by RSXR. The derived optical constants from the measured RSXR data suggested the presence of excess carbon into the boron carbide layer. [ABSTRACT FROM AUTHOR]

By using full three-dimensional particle-in-cell and Monte Carlo simulations, we investigate the generation of a high-brightness attosecond x-ray pulse train in a double-laser-driven cone target. The scheme makes use of two lasers: the first high-intensity laser with a laser peak intensity 1.37 × 1020W/cm2 irradiates the cone and produces overdense attosecond electron bunches; the second counterpropagating weakly relativistic laser with a laser peak intensity 4.932 × 1017W/cm2 interacts with the produced electron bunches and a bright x-ray pulse train is generated by Thomson backscattering of the second laser off the attosecond electron bunches. It is shown that the photon flux rises by 5 times using the cone target as compared with a normal channel. Meanwhile, the x-ray peak brightness increases significantly from 1.4 × 1021/(s mm2 mrad2 0.1 keV) to 6.0 × 1021/(s mm2 mrad2 0.1 keV), which is much higher than that of the Thomson x-ray source generated from traditional accelerators. We also discuss the influence of the laser and target parameters on the x-ray pulse properties. This compact bright x-ray source may have diverse applications, e.g., the study of electric dynamics and harmonics emission in the atomic scale. [ABSTRACT FROM AUTHOR]

We report on the experimental realization of propagation-based x-ray microscopy with laboratory sources equipped with waveguides. We discuss about the experimental setup, the fabrication steps, and the characterization procedures of the waveguide optics. We demonstrate that the system enables high resolution attenuation imaging of poorly absorbing biological specimens. Furthermore, we report the successful realization of propagation-based phase contrast x-ray microscopy, enabling quantitative thickness estimation in homogeneous objects. Advantages and major limitations of the experimental scheme are presented and discussed. [ABSTRACT FROM AUTHOR]

We report on the relationship between structural and magnetic properties, as well as their Mnsubstitution dependence for ceramics Ba(CoCo1-xMnx)O3 (x=0.00-0.30) following an analysis using synchrotron X-ray spectroscopy. The crystal structure of samples of Ba(CoCo1-xMnx)O3 ceramics changed from 2H- to 10H- through 12H-type phases depending on composition ratio x. The saturation magnetization increased in the presence of the 12H-type phase, and decreased in the presence of the 10H-type phase; a maximum value of 2.49 μB/f.u. at 5K is obtained with composition ratio x=0.1. The correlation between structural and magnetic properties as well as their dependence on Mn substitution are explained by the preferential occupation of the cubic stacking sites by Mn ions. The 12H-type phase exhibited ferri-magnetic ordering attributed to the ferromagnetic superexchange coupling of Co4+(d5)-O2--Mn4+(d3) with a bonding angle of 180°; the 2H- and 10H-type phases exhibited anti-ferromagnetic ordering attributed to the anti-ferromagnetic super-exchange couplings of Co4+(d5) -O2--Co4+(d5) and Co4+(d5) -O2--Mn4+(d3), respectively, with a bonding angle of 90°. The saturation magnetization therefore increases with the presence of the ferromagnetic 12H-type phase, whereas it decreases in the presence of the anti-ferromagnetic 10H-type phase. [ABSTRACT FROM AUTHOR]