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We present an investigation of the microstructure changes in V2O3 as it goes through its inherent structural phase transition. Using V2O3 films with a well-defined crystal structure deposited by reactive magnetron sputtering on r-plane Al2O3 substrates, we study the phase coexistence region and its impact on the surface roughness of the films and the magnetic properties of overlying Ni magnetic layers in V2O3/Ni hybrid magnetic heterostructures. The simultaneous presence of two phases in V2O3 during its structural phase transition was identified with high resolution x-ray diffraction and led to an increase in surface roughness observed using x-ray reflectivity. The roughness reaches its maximum at the midpoint of the transition. In V2O3/Ni hybrid heterostructures, we find a concomitant increase in the coercivity of the magnetic layer correlated with the increased roughness of the V2O3 surface. The chemical homogeneity of the V2O3 is confirmed through transmission electron microscopy analysis. High-angle annular dark field imaging and electron energy loss spectroscopy reveal an atomically flat interface between Al2O3 and V2O3, as well as a sharp interface between V2O3 and Ni. [ABSTRACT FROM AUTHOR]

Magnetite has long been investigated across many disciplines due to the interplay between its ferroic order parameters, namely, its ferrimagnetism, ferroelasticity, and ferroelectricity. Despite this, the experimental difficulty in measuring low temperature real space images of the ferroelectric domains has meant that the local behavior of ferroelectric domains emergent below the ∼ 38 K phase transition have yet to be realized. This work presents real space images of the ferroelectric domains and uses piezoresponse force microscopy as a function of temperature to probe the onset of piezoelectricity and ferroelectricity across the 38 K transition. [ABSTRACT FROM AUTHOR]

Rare earth (RE):transition metal (TM) ferrimagnetic alloys continue to attract significant attention for spintronics. This work focuses on the elemental distribution of RE and TM elements throughout the thickness of nominally uniform films and the resulting spatial variations of the magnetization within these layers. Samples of CoFe alloyed with Gd were studied using secondary ion mass spectroscopy, polarized neutron reflectometry, and x-ray resonant magnetic reflectivity. The samples were grown by magnetron co-sputtering to control the RE:TM alloy ratio of the ferrimagnetic layer, which was combined with W and Pt layers as either under or over-layers to create sample structures such as W / Gd x (Co 70 Fe 30) 100 − x / Pt , where x = 0, 8, and 23 at. %. Results show that uniformly deposited thin-films have a significant variation in the distribution of the TM and RE through the film thickness, and this leads to a spatial distribution in the net magnetization profile and a non-uniform Gd magnetization profile within the layer. These findings have implications for the application RE:TM alloys in spintronics as they may impact the perpendicular magnetic anisotropy, the ferrimagnetic compensation temperature, and interfacial spin transport. [ABSTRACT FROM AUTHOR]

The relationship between proximity-induced magnetism (PIM) at the heavy metal/ferromagnet interface and spin-transport across such interfaces has generated significant debate. To investigate the link between the two, element specific x-ray magnetic circular dichroism and ferromagnetic resonance measurements were made on the same CoFe/Au/Pt and NiFe/Au/Pt thin film samples with varying Au thickness, with complementary SIMS analysis, which shows evidence of Ni diffusion from NiFe into the Pt. An approximately linear relationship is observed between the magnitude of Pt PIM and magnitude of damping enhancement in both systems. The results demonstrate that electronic hybridization of the heavy metal and ferromagnet is required for a full understanding of damping enhancement and interfacial spin-transport for spintronic devices. [ABSTRACT FROM AUTHOR]

The structure of nitride containing gold films produced by reactive ion sputtering and nitrogen plasma etching is investigated using x-ray photoelectron spectroscopy and x-ray diffraction. It is found that gold nitride is a solid solution of nitrogen atoms dissolved in a fcc gold matrix. Differences between the strain and lattice parameters of gold and gold nitride films were observed and are explained by interstitial nitrogen present in the latter. [ABSTRACT FROM AUTHOR]

We report the direct epitaxial growth of equiatomic ordered antiferromagnetic PtMn layers by molecular beam epitaxy. Such layers are used in giant magnetoresistance spin valve sensors as the antiferromagnetic pinning layer. Structural characterization and phase identification confirmed the spontaneous formation of the chemically ordered face-centered-tetragonal (L10) phase of PtMn with about 87.4% ordering. Based on the antiferromagnetic PtMn layer, we prepared exchange-biased PtMn/NiFe bilayers with various PtMn thicknesses. The exchange anisotropy field of the bilayer with NiFe grown on PtMn stabilizes at about 50 Oe beyond a PtMn thickness of 15 nm. Although the exchange anisotropy field is small compared to that of the polycrystalline system, the antiferromagnetic domain structure is stable over repetitive external magnetic field cycling and no training effect is observed. [ABSTRACT FROM AUTHOR]

The correlation between grain size and intermixing in sputter-deposited bilayers of the form X/Al and Al/X (where X=Ta, W, Ir, and Os) has been investigated by in-plane grazing-incidence x-ray diffraction. We have found no correlation between grain size and intermixing at the interface and our data provide strong evidence against the postulate that the asymmetry in intermixing arises from the Harrison type-C mechanism of fast diffusion along grain boundaries or dislocations. [ABSTRACT FROM AUTHOR]

Transparent p-type conducting CuGaO[sub 2] thin films were prepared on α-A1[sub 2]O[sub 3] (001) single-crystal substrates by pulsed laser deposition. The films were grown epitaxially on the substrates in an as-deposited state. X-ray pole figure analysis revealed that the films were composed of two types of epitaxial grains, both with c axes oriented perpendicular to the surface and a axes rotated 60° with respect to each other around the c axis. Observation of the CuGaO[sub 2] thin films by atomic force microscopy and high-resolution transmission electron microscopy substantiated this conclusion. The films have high optical transparency (∼80%) in the visible region, and the energy gap of CuGaO[sub 2] for direct allowed transition was estimated to be 3.6 eV. p-type conductivity was confirmed by Seebeck and Hall measurements. The electrical conductivity, carrier (positive hole) density, and Hall mobility of the films at room temperature were 6.3 x 10[sup -2] S cm[sup -1], 1.7 x 10[sup 18] cm[sup -3], and 0.23 cm²V[sup -1]s[sup -1], respectively. [ABSTRACT FROM AUTHOR]

States that substrate bias voltages are effective in preparing high-quality laser-deposited superconducting Ba[sub2]Y[sub1]Cu[sub3]O[sub7-x] thin films at reduced substrate temperatures. Zero resistance temperature of the biased thin films; Effectiveness of positive bias than negative bias; Surface morphology and c-axis orientation.

Using the surface, interface, and element specificity of x-ray resonant magnetic scattering in combination with x-ray magnetic circular dichroism, we have spatially resolved the polarization, and hence the spin accumulation in Mn high susceptibility material in close proximity to a ferromagnetic layer. The magnetic polarization of Mn and Cu 3d electrons in paramagnetic CuMn layers is detected in a Co/Cu(x)/CuMn structure for varying copper layer thicknesses (x). The size of the Mn and Cu L2–3-edge dichroism shows a decrease in the polarization for increasing copper thickness indicating the dominant interfacial nature of the Cu and Mn spin polarization. The Mn polarization appears to be much higher than that of Cu. [ABSTRACT FROM AUTHOR]

La0.67Ca0.33MnO3 (LCMO) thin films with the thickness varying from 200 to 500 Å have been deposited by magnetron sputtering on sapphire, SrTiO3, yttrium-stabilized ZrO2 substrates. A metal-to-insulator transition behavior was observed for all samples with the transition temperature and width varying with the substrate and the film thickness. A percolation model has been used to obtain the physical parameters on low-temperature metallic transport behavior and the adiabatic thermal small polaron hopping progress. The surface of the deposited films was measured by atomic force microscopy and grazing incidence x-ray specular and diffuse scattering. Fits to the data show the presence of a mixed layer between the substrate and the LCMO films the extent of which depends on the substrate used. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Electron scattering mechanisms within metallic multilayers are affected by both structural and magnetic disorders. Off-specular x-ray scattering has long been used to probe the structural interfaces, and it is only recently that it has been applied to the study of magnetic disorder. We compare the resonant magnetic x-ray scattering with off-specular neutron studies from magnetron-sputtered Co/Cu and Co/Ru multilayers grown at the second antiferromagnetic coupling peak. Both techniques yield similar results for the Cu system, and a simple domain model can be applied to extract the magnetic interface morphological parameters. For the Cu system, the in-plane correlation length is field dependent and is 880 ± 20 Å after saturation along the hard axis, but increases to 7000 ± 100 Å after saturation along the orthogonal easy axis. Both systems show strong out-of-plane correlations in both the structural and magnetic disorders. In all cases, the out-of-plane correlation length for the structural interfaces is 200-250 Å, but the ratio of the magnetic to structural correlations length is dependent on the magnitude of the exchange coupling and ranges from 0.4 to 1.4. [ABSTRACT FROM AUTHOR]

Grazing incidence x-ray scattering has been used to study interfacial intermixing in thin films of aluminum/transition metal bilayers grown by dc magnetron sputter deposition at room temperature. As with all transition metals, the ferromagnets Fe, Co and Ni have dramatically different interface widths between X/Al and Al/X (X=Fe,Co,Ni). Intermixing lengths are larger for X on Al than for Al on X. [ABSTRACT FROM AUTHOR]

The strong interdiffusion that takes place in the Gd/Co multilayered system greatly influences the structure, composition, and thus the magnetic properties of the layers. We have conducted grazing incidence x-ray scattering experiments using synchrotron radiation on Gd[SUB1-x]Co[SUBx]/Co multilayers with x = 0, 0.37 and x = 0.60 to study the interdiffusion process that takes place and the interfacial structure that results. Probing the scattering vector normal to the surface (specular scattering) showed excellent multilayer growth for all samples. For alloyed Gd samples, good multilayer growth was observed with Co thickness down to below 6 Å. Fits to the reflectivity data show a reduction in the thickness of the Co layer, significantly away from its nominal value. This effect was more exaggerated in the pure Gd sample (x = 0). We have successfully modeled this by assuming a significant portion of the Co has interdiffused into the pure Gd layer. Off-specular scattering experiments show that the interface roughness was conformal in all samples and was not related to the interdiffusion processes at the interfaces. [ABSTRACT FROM AUTHOR]

This document is an erratum for an article titled "Non-uniform Gd distribution and magnetization profiles within GdCoFe alloy thin films" published in Applied Physics Letters. The erratum corrects an error in the composition of one of the materials used in the original article. The correct composition is Co30Fe70, not Co70Fe30 as previously stated. The legends and caption for Figure 2 have been updated to reflect the correct composition. The erratum states that all other results, discussions, and conclusions in the original article remain the same. [Extracted from the article]

A new materials characterization system developed at the XMaS beamline, located at the European Synchrotron Radiation Facility in France, is presented. We show that this new capability allows to measure the atomic structural evolution (crystallography) of piezoelectric materials whilst simultaneously measuring the overall strain characteristics and electrical response to dynamically (ac) applied external stimuli. [ABSTRACT FROM AUTHOR]

Although magnetic heterostructures are the basis of many magnetic technologies, the mechanisms involved in magnetization reversals in such structures are not fully understood, especially in amorphous multilayers. Here, we report on the SmCo/CoAlZr system and exploit resonant magnetic x-ray scattering to probe the element specific magnetization reversals. When combined into a tri-layer structure, two different switching fields and reversal mechanisms are observed for the Sm and Co sub-lattices. We argue that the decoupling of the sub-lattices arises from the local distribution of atomic species within the amorphous matrix leading to a strong magnetic leverage effect and exchange pinning. The decoupling arises due to strong interactions between regions of high Co density which span the interface. The relatively sparse interactions between Sm and Co induce a localized pinning of the Co-rich areas, resulting in an exchange bias in minor loops and an enhanced coercivity. [ABSTRACT FROM AUTHOR]

The influence of interfacial intermixing on the picosecond magnetization dynamics of ferromagnetic/non-magnetic thin-film bilayers was studied. Low-dose focused-ion-beam irradiation was used to induce intermixing across the interface between a 10 nm Ni81Fe19 layer and a 2-3 nm capping layer of either Au or Cr. Time-resolved magneto-optical Kerr effect was used to study magnetization dynamics as a function of ion-beam dose. With an Au cap, the damping of the un-irradiated bilayer was comparable with native Ni81Fe19 and increased with increasing ion dose. In contrast, for Ni81Fe19/Cr the damping was higher than that for native Ni81Fe19, but the damping decreased with increasing dose. [ABSTRACT FROM AUTHOR]

We report the design and construction of a novel soft x-ray diffractometer installed at Diamond Light Source. The beamline endstation RASOR is constructed for general users and designed primarily for the study of single crystal diffraction and thin film reflectivity. The instrument is comprised of a limited three circle (θ, 2θ, and χ) diffractometer with an additional removable rotation ([lowercase_phi_synonym]) stage. It is equipped with a liquid helium cryostat, and post-scatter polarization analysis. Motorized motions are provided for the precise positioning of the sample onto the diffractometer center of rotation, and for positioning the center of rotation onto the x-ray beam. The functions of the instrument have been tested at Diamond Light Source, and initial test measurements are provided, demonstrating the potential of the instrument. [ABSTRACT FROM AUTHOR]

The barrier thickness in magnetic spin-dependent tunnel junctions with Al[sub 2]O[sub 3] barriers has been measured using grazing incidence x-ray reflectivity and by fitting the tunneling current to the Simmons model. We have studied the effect of glow discharge oxidation time on the barrier structure, revealing a substantial increase in Al[sub 2]O[sub 3] thickness with oxidation. The greater thickness of barrier measured using grazing incidence x-ray reflectivity compared with that obtained by fitting current density-voltage to the Simmons electron tunneling model suggests that electron tunneling is localized to specific regions across the barrier, where the thickness is reduced by fluctuations due to nonconformal roughness. [ABSTRACT FROM AUTHOR]

Magnetite has long been investigated across many disciplines due to the interplay between its ferroic order parameters, namely, its ferrimagnetism, ferroelasticity, and ferroelectricity. Despite this, the experimental difficulty in measuring low temperature real space images of the ferroelectric domains has meant that the local behavior of ferroelectric domains emergent below the ∼ 38 K phase transition have yet to be realized. This work presents real space images of the ferroelectric domains and uses piezoresponse force microscopy as a function of temperature to probe the onset of piezoelectricity and ferroelectricity across the 38 K transition. [ABSTRACT FROM AUTHOR]

Examines the molecular beam epitaxy technique for growing oxides using low-energy and high-density oxygen-ion beams. Simultaneous deposition of copper metal on magnesium oxide(100); Potential of oxygen beams for oxidation; Formation of copper oxide.

SmCo thin films have been grown by magnetron sputtering at room temperature with a composition of 2-35 at. % Sm. Films with 5 at. % or higher Sm are amorphous and smooth. A giant tunable uniaxial in-plane magnetic anisotropy is induced in the films which peaks in the composition range 11-22 at. % Sm. This cross-over behavior is not due to changes in the atomic moments but rather the local configuration changes. The excellent layer perfection combined with highly tunable magnetic properties make these films important for spintronics applications. [ABSTRACT FROM AUTHOR]

We present evidence from soft x-ray resonant magnetic scattering measurements at the Mn L[sub 3] edge for the existence of a small magnetic moment on the antiferromagnetic IrMn pinning layer in a NiFe/Cu/Co/IrMn spin valve structure. The variation of the signal in an applied magnetic field shows that the moment lies antiparallel to the Co moment. Changes in the Mn L[sub 3] edge signal as the Co moment is rotated into the hard direction are rapid and do not appear to be associated with thermal reordering of the antiferromagnetic domain structure. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Achieving a higher magnetic field is important for solid-state nuclear magnetic resonance (NMR). But a conventional low temperature superconducting (LTS) magnet cannot exceed 1 GHz (23.5 T) due to the critical magnetic field. Thus, we started a project to replace the Nb(3)Sn innermost coil of an existing 920 MHz NMR (21.6 T) with a Bi-2223 high temperature superconducting (HTS) innermost coil. Unfortunately, the HTS magnet cannot be operated in persistent current mode; an external dc power supply is required to operate the NMR magnet, causing magnetic field fluctuations. These fluctuations can be stabilized by a field-frequency lock system based on an external NMR detection coil. We demonstrate here such a field-frequency lock system in a 500 MHz LTS NMR magnet operated in an external current mode. The system uses a (7)Li sample in a microcoil as external NMR detection system. The required field compensation is calculated from the frequency of the FID as measured with a frequency counter. The system detects the FID signal, determining the FID frequency, and calculates the required compensation coil current to stabilize the sample magnetic field. The magnetic field was stabilized at 0.05 ppm∕3 h for magnetic field fluctuations of around 10 ppm. This method is especially effective for a magnet with large magnetic field fluctuations. The magnetic field of the compensation coil is relatively inhomogeneous in these cases and the inhomogeneity of the compensation coil can be taken into account.

We have shown from in situ synchrotron x-ray diffraction measurements that there are two thermodynamically stable liquid forms of SnI(4), depending on the pressure. Based on the liquid-liquid critical point scenario, our recent measurements suggest that the second critical point, if it exists, may be located in a region close to the point at which the melting curve of the crystalline phase abruptly breaks. This region is, unlike that of water, experimentally accessible with relative ease., (© 2011 American Institute of Physics)

The discovery of a first-order phase transition in fluid phosphorus aroused renewed interest in polyamorphism in liquids with a locally tetrahedral molecular structure. We have performed in situ synchrotron x-ray diffraction measurements on tin tetraiodide, which consists of SnI(4) tetrahedral molecules at ambient pressure, and established that the liquid forms existing above and below 1.5 GPa, where the slope of the melting curve of the solid phase changes abruptly, have different structures. This discovery offers evidence of thermodynamically stable polyamorphism in general compounds as well as in elements. A possible phase diagram that includes the two amorphous states already found is proposed based on the pseudobinary regular solution model. The vertex-to-face orientation between the nearest molecules plays a key role in the transition from the low-pressure to the high-pressure liquid phase.