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We report on the x-ray absorption spectra (XAS) and x-ray magnetic circular dichroism (XMCD) of a series of NiFe 2 O 4 (Ni ferrite) films grown on symmetry matched substrates and measured in two geometries: out-of-plane and near in-plane. The Ni ferrite films, grown by pulsed laser deposition, are epitaxial and the substrates used (ZnGa 2 O 4 , CoGa 2 O 4 , MgGa 2 O 4 , and MgAl 2 O 4) introduce a systematic variation in the lattice mismatch between the substrate and the film. Modeling of the XAS and XMCD spectra, both measured with the surface sensitive total electron yield mode, indicates that the Ni 2 + cations reside on the octahedrally coordinated lattice sites in the spinel structure. Analyses of the Fe XAS and XMCD spectra are consistent with Fe 3 + cations occupying a subset of the octahedral and tetrahedral sites in the spinel oxide lattice with the addition of a small amount of Fe 2 + located on octahedral sites. The Ni 2 + orbital to spin moment ratio (μ ℓ / μ s), derived from the application of XMCD sum rules, is enhanced for the substrates with a small lattice mismatch relative to NiFe 2 O 4. The results suggest a path for increasing the orbital moment in NiFe 2 O 4 by applying thin film growth techniques that can maintain a highly strained lattice for the NiFe 2 O 4 film. [ABSTRACT FROM AUTHOR]

We report on an all-optical investigation of coupled spin excitation modes in a series of magnetic trilayer structures. Using time-resolved magneto-optic Kerr effect (tr-MOKE) magnetometry, we observe multi-mode coherent spin excitations in Ni 81 Fe 19 /Ru/ Co 49 Fe 49 V 2 multilayers even though the tr-MOKE optical detection is sensitive only to the Co 49 Fe 49 V 2 magnetization dynamics. Frequency shifts of the different modes indicate that the coupling between the Ni 81 Fe 19 and Co 49 Fe 49 V 2 layers varies from anti-ferromagnetic to ferromagnetic to uncoupled as the Ru spacer layer thickness is increased from 8 Å to 200 Å. The lifetime of the high frequency coherent oscillations in the Co 49 Fe 49 V 2 layer increases by over 200%–300% even in the case of uncoupled Ni 81 Fe 19 and Co 49 Fe 49 V 2 layers with a 200 Å thick Ru spacer. The results suggest an additional method to decrease the damping of high-moment alloys in layered magnetic nanostructures. [ABSTRACT FROM AUTHOR]

We present all-optical studies of spin dynamics in two classes of ferrimagnets. Both sets of experiments use table-top laser-based pump–probe techniques to examine the ultrafast and longer timescale spin excitations. We use the visible/near infra-red time-resolved magneto-optical Kerr effect (tr-MOKE) to follow the spin dynamics of a series of metallic (FeCo) 1 − x Gd x thin films with varying Gd content. Magnetic compensation in the films occurs at a Gd concentration of ≈ 26 % , and the spin dynamics of the films exhibit a non-monotonic variation in effective magnetization. We also examine spin dynamics in an insulating NiFe 2 O 4 spinel using ultrafast techniques up at extreme ultraviolet energies, which permit element-specific investigations. The element and time-resolved delay scans reveal a non-trivial interaction between spin excitations on the different magnetic sub-lattices of the magnetic insulator. [ABSTRACT FROM AUTHOR]

Many technologically useful magnetic oxides are ferrimagnetic insulators, which consist of chemically distinct cations. Here, we examine the spin dynamics of different magnetic cations in ferrimagnetic NiZnAl-ferrite (Ni0.65Zn0.35Al0.8Fe1.2O4) under continuous microwave excitation. Specifically, we employ time-resolved x-ray ferromagnetic resonance to separately probe Fe2+/3+ and Ni2+ cations on different sublattice sites. Our results show that the precessing cation moments retain a rigid, collinear configuration to within ≈ 2°. Moreover, the effective spin relaxation is identical to within <10% for all magnetic cations in the ferrite. Thus, we validate the oft-assumed "ferromagnetic-like" dynamics in the resonantly driven ferrimagnetic oxide: the magnetic moments from different cations precess as a coherent, collective magnetization, despite the high contents of nonmagnetic Zn2+ and Al3+ diluting the exchange interactions. [ABSTRACT FROM AUTHOR]

Spin gapless semiconductors are known to be strongly affected by structural disorder when grown epitaxially as thin films. The magnetic properties of Mn2CoAl thin films grown on GaAs (001) substrates are investigated here as a function of annealing. This study investigates the atomicspecific magnetic moments of Mn and Co atoms measured through X-ray magnetic circular dichroism as a function of annealing and the consequent structural ordering. The results indicate that the structural distortion mainly affects the Mn atoms as seen by the reduction of the magnetic moment from its predicted value. [ABSTRACT FROM AUTHOR]

We report on x-ray and neutron scattering studies that reveal the structure of interfaces of C60 layers with adjacent transition metal layers, in this instance, Cu. Such interfaces produce room-temperature long-range spin order that is not described by conventional theories of metallic magnetism. We use a combination of hard x-ray reflectivity and neutron scattering to investigate the interfacial structure of two C60/Cu layered samples: a superlattice with multiple C60/Cu repeats and a simpler tri-layer structure. For both structures, we develop a consistent structural model for the two scattering techniques, which details the critical interfacial roughness between the layers. We find that while x-ray reflectivity provides a strong contrast between the C60 and Cu layers, the similar neutron scattering length density of the two materials severely reduces the neutron scattering contrast. Our results can be used to design material systems that permit studies of the magnetism of the C60/transition metal interfaces with spin-sensitive scattering probes such as polarized neutron reflectometry. [ABSTRACT FROM AUTHOR]

We present measurements of element- and time-resolved ferromagnetic resonance (FMR) in magnetic thin films at gigahertz frequencies via an implementation of time-resolved x-ray magnetic circular dichroism (TR-XMCD). By combining TR-XMCD and FMR, using a rf excitation that is phase locked to the photon bunch clock, the dynamic response of individual layers or precession of individual elements in an alloy can be measured. The technique also provides extremely accurate measurements of the precession cone angle (to 0.1°) and the phase of oscillation (to 2°, or ∼5 ps at 2.3 GHz). TR-XMCD combined with FMR can be used to study the origins of precessional damping by measuring the relative phase of dissimilar precessing magnetic moments. We have used the technique to measure the response of specific elements and separate layers in several alloys and structures, including a single Ni81Fe19 layer, a pseudo-spin-valve structure (Ni81Fe19/Cu/Co93Zr7), magnetic bilayers consisting of low damping (Co93Zr7) and high damping (Tb-doped Ni81Fe19) layers joined across a common interface, and elemental moments in Tb-doped Ni81Fe19. [ABSTRACT FROM AUTHOR]

The surface, interface and element specificity of x-ray resonant magnetic scattering in combination with x-ray magnetic circular dichroism are used for spatially resolving the polarization and the spin accumulation in Mn high susceptibility material in close proximity to a ferromagnetic layer. The size of the Mn and Cu [L.sub.2-3]-edge dichroism has shown a decrease in the polarization for increasing copper thickness indicating the dominant interfacial nature of the Cu and Mn spin polarization.

Annealing is necessary to achieve giant tunneling magnetoresistance (TMR) values in sputtered CoFeB/MgO/CoFeB magnetic tunnel junctions (MTJs). In this study three complementary techniques were used to study the resulting changes in junction microstructure. The as-deposited TMR was modest, 5%, but rose to 101% after annealing at 325 °C for 1 h, corresponding to the tunneling spin polarization rising from 16% to 58%. Soft x-ray resonant magnetic scattering showed a roughening of the magnetic interfaces of the MTJ free layer, confirmed by transmission electron microscopy, which also showed the changes in the CoFeB and MgO to a lattice-matched polycrystalline form. [ABSTRACT FROM AUTHOR]

Epitaxial Fe48Rh52 thin films of nominal thickness 500 Å were grown on MgO (001) substrates via molecular beam epitaxy and capped with 20 Å of either Au or MgO. The presence of the anticipated magnetostructural phase transition from antiferromagnetism to ferromagnetism at ∼350 K was confirmed by superconducting quantum interference device and magneto-optic Kerr effect magnetometry. X-ray magnetic circular dichroism (XMCD) experiments were carried out at the L2,3 edges; measurements were done in both total electron yield (TEY) mode and indirect transmission mode. At room temperature, the indirect transmission XMCD data show no detectable dichroism, consistent with bulk antiferromagnetic behavior. However, room-temperature TEY data originating from the films’ surface reveal an appreciable dichroic signal indicating the presence of ferromagnetism. This near-surface/interfacial magnetism may be modified by choice of capping layer; the MgO-capped sample exhibited a considerably smaller ferromagnetic XMCD signal. The results have potential impact on the application of FeRh thin films as temperature-variable pinning layers in exchanged-biased systems. [ABSTRACT FROM AUTHOR]

Self-assembled arrays of nanospheres have been used to pattern a Co/Pt multilayer into nanopillars. On top of this has been deposited a Co/Ru multilayer, which is antiferromagnetically coupled. The nanopillars introduce a known structural and magnetic lateral modulation into the multilayer. Soft x-ray magnetic scattering was used to observe the interference patterned from the patterned substrate. This has allowed us to show how the magnetic roughness correlates with the structural roughness and obtain selective magnetometry of the various magnetic elements. [ABSTRACT FROM AUTHOR]

The in-plane magnetic properties of Co0.7Fe0.3 films sputtered onto Al0.1Ga0.9As and Al0.1Ga0.9As/GaAs epilayers are consistent with a strongly oriented bcc crystal structure with clean metal-semiconductor interfaces. However, the interface induced uniaxial magnetic anisotropy is oriented along one of the in-plane <100>, rather than <110>, as is the case in molecular beam epitaxy—grown films. Resonant x-ray measurements show interfacial magnetic disorder in films on Al0.1Ga0.9As, which accounts for the difference in magnetic anisotropy behavior between samples on Al0.1Ga0.9As and Al0.1Ga0.9As/GaAs epilayer substrates, and which may have significant consequences for the spin-injection efficiency across such interfaces. [ABSTRACT FROM AUTHOR]

The nature of the metal-insulator transition in thin films and superlattices of LaNiO3 only a few unit cells in thickness remains elusive despite tremendous effort. Quantum confinement and epitaxial strain have been evoked as the mechanisms, although other factors such as growth-induced disorder, cation non-stoichiometry, oxygen vacancies, and substrate–film interface quality may also affect the observable properties of ultrathin films. Here we report results obtained for near-ideal LaNiO3 films with different thicknesses and terminations grown by atomic layer-by-layer laser molecular beam epitaxy on LaAlO3 substrates. We find that the room-temperature metallic behavior persists until the film thickness is reduced to an unprecedentedly small 1.5 unit cells (NiO2 termination). Electronic structure measurements using X-ray absorption spectroscopy and first-principles calculation suggest that oxygen vacancies existing in the films also contribute to the metal-insulator transition. [ABSTRACT FROM AUTHOR]

We present experimental techniques to measure magnetization precession of individual layers in a “spin-valve” trilayer. Precessional motions of individual Ni81Fe19 and Co93Zr7 layers have been separated in Ni81Fe19/Cu/Co93Zr7 using ±45 ps time-resolved x-ray magnetic circular dichroism (tr-XMCD) at Fe and Co edges. We compare the efficacy of two experimental configurations in this paper. Pulsed-field tr-XMCD measurements in reflectivity are compared with resonant-field tr-XMCD measurements in transmission. Despite the order of magnitude larger angles of precession excited in pulsed-field reflectivity measurements, data quality is found to be superior in resonant-field transmission measurements. Relative roles of sample preparation and timing jitter in the different techniques are discussed. [ABSTRACT FROM AUTHOR]

Co2MnSi thin films were grown on Al2O3 sa planed and GaAs (001) substrates and on thin silicon nitride windows using pulsed laser deposition. Angle-dependent magneto-optic Kerr effect measurements reveal both a uniaxial and a fourfold magnetocrystalline anisotropy for films grown on GaAs (001). X-ray magnetic circular dichroism spectra were measured at the L2,3 edges of the thin films as a function of aluminum cap layer thickness, and transmission mode L2,3 x-ray absorption through a 1000-Å Co2MnSi film grown on a silicon nitride membrane were measured, indicating that deviations from metalliclike spectra are likely due oxidation or contamination. Element-specific moments for Co and Mn were calculated from the X-ray magnetic circular dichroism data of a nonoxidized film. [ABSTRACT FROM AUTHOR]

We present transmission-mode XMCD characterization of Fe, Ni, and Tb moment alignment in Tb-doped Ni81Fe19 thin films. The use of transmission geometry measurements has allowed the extraction of absolute projected elemental moments in the alloy. A very low projected Tb moment at 6% doping level, which nonetheless reverses with low applied fields (40 Oe), indicates a sperimagnetic alignment with respect to the Fe and Ni elements in the cosputtered polycrystalline alloy. [ABSTRACT FROM AUTHOR]

The article looks at a study that investigates symmetry breaking of the magnetic vortex state in nanoscopic ferromagnetic elements before annihilation. Topics discussed include properties of solitons undergoing structural breakdown, destabilization of the soliton through Zeeman and demagnetization interaction, and identification of the core polarity through the asymmetric states of elements.

Nanoislands of α'-FeRh were formed by the deposition of a 10 nm film onto (0 0 1)-MgO and observed by atomic force microscopy. This island-like architecture results in stabilized ferromagnetic (FM) ordering at low temperatures as noted by asymmetry in the x-ray diffraction peaks, a magnetostructural transition with a large magnetic background signal, and broad thermal hysteresis. The combination of structural and magnetic results suggest that the crystallographic arrangement of the FeRh nanoislands consists of a gradient of lattice parameters where there is a compressed inner region of lower lattice parameter values (attributed to antiferromagnetic ordering) which gradually relaxes outward to a region of larger lattice parameters (attributed to a retained FM ordering). The impact of this configuration on magnetostructural transformation is discussed in the context of classical nucleation theory. [ABSTRACT FROM AUTHOR]

We investigated thin La0.7Sr0.3MnO3-SrTiO3 heterostructures, where the band alignment is engineered by a variation of La/Sr stoichiometry only at the interface. In thin films, the engineered interface leads to an enhancement of the reversed spin configuration that mimics bulk behavior. Microscopically, this enhancement is closely connected with an increased magnetic anisotropy as well as intercoupling between an eg orbital reconstruction and a corresponding anisotropic lattice fluctuation. Furthermore, a reentrant-type behavior, triggered by this intercoupling, is observed in the remanent spin state. This microscopic perspective leads to insights on developing new strategies for maintaining bulk-like properties even in very thin La0.7Sr0.3MnO3 heterostructures. [ABSTRACT FROM AUTHOR]

We present a compact sample holder equipped with electromagnets and high frequency transmission lines; the sample holder is intended for combined x-ray magnetic circular dichroism (XMCD) and ferromagnetic resonance measurements (FMR). Time-resolved measurements of resonant x-ray detected FMR during forced precession are enabled by use of a rf excitation that is phase-locked to the storage ring bunch clock. Several applications of the combined XMCD+FMR technique are presented, demonstrating the flexibility of the experimental design. [ABSTRACT FROM AUTHOR]

We present an entrance slitless beamline design capable of maintaining its very high performance in terms of energy resolution (>104) and spot size (4×4 μm2) at the sample position despite being exposed to more than 2.15 kW of undulator radiation and a maximum power density on the optics of more than 0.9 W/mm2. Ray tracing simulations of this beamline under the worst-case thermal deformations of the optical element surfaces verify that appropriate focusing corrections are able to cancel the deleterious effects of these deformations. One of the necessary conditions for this cancellation is to illuminate the optical elements with a larger solid angle than the undulator’s central cone, which contains the usable photons but is considerably smaller than the angular power distribution. [ABSTRACT FROM AUTHOR]

Fe ions were implanted into well-aligned single-crystal ZnO nanotips grown on SiO2/quartz substrates using metal-organic chemical vapor deposition (MOCVD). The Fe ion concentration distribution within a single nanotip is mapped by electron energy loss spectroscopy (EELS) and energy dispersive spectroscopy (EDS) and the nanotips imaged by high-resolution transmission electron microscopy (TEM). X-ray absorption spectroscopy (XAS) identified the presence of Fe2+ and Fe3+ ions in both as-implanted and annealed samples. However, Fe3+ ion concentration increased during postannealing. Superconducting quantum interference device (SQUID) measurements show that the as-implanted and postannealed ZnO nanotips are ferromagnetic at room temperature. The observed ferromagnetism in the as-implanted nanotips is primarily attributed to the near surface 10-nm region that has high Fe concentration. The saturation magnetization reduces after annealing. [ABSTRACT FROM AUTHOR]

O1s and Mn2p near-edge X-ray absorption spectroscopy on La1-xSr1+xMnO4 (0 ≤x ≤0.5) single crystals shows that Sr doping does not only provide holes to the system but also induces a continuous transfer of electrons from out-of-plane d3z2-r2 to in-plane d3x2-r2/d3y2-r2 orbitals. Furthermore, a non-vanishing electron occupation of in-plane dx2-y2 and out-of-plane d3z2-r2 orbitals is observed up to relatively high doping contents. These findings demonstrate that the energy difference between all these orbital types has to be very small and manifest that the orbital degree of freedom is determined not just by crystal field effects but also by orbital coupling. Moreover, the doping-dependent transfer of spectral weight observed in the current data identifies La1-xSr1+xMnO4 as a charge-transfer insulator. [ABSTRACT FROM AUTHOR]

A hybrid mode matching (MM)-finite element (FE) technique is presented, with application to the analysis of waveguide components and inductive frequency selective surfaces (FSSs). The proposed hybrid approach combines the computational efficiency of the MM analysis with the versatility and flexibility of the FE method. One of the key features of the present formulation is the expansion of transverse electric and magnetic fields by using tangential vector edge elements (TVEEs), which guarantee spurious-free solutions; indeed, this property is very important for an accurate numerical determination of the modal eigenvalues. FSSs, realized by periodically perforating thick metallic screens with arbitrarily shaped apertures, are analyzed by expanding the electromagnetic fields in the free-space region through a complete set of Floquet modes that allows us to reduce the analysis to the single periodicity cell; modes inside apertures are determined through a FEM procedure. A spectral criterion to determine the correct ratio between the number of FEM-reconstructed and analytically derived modes is adopted. Samples of numerical results are shown in order to check both the effectiveness and the accuracy of the proposed procedure. [ABSTRACT FROM AUTHOR]

We present time- and element-resolved measurements of the magnetization dynamics in a ferromagnetic trilayer structure. A pump-probe scheme was utilized with a microwave magnetic excitation field phase-locked to the photon bunches and x-ray magnetic circular dichroism in transmission geometry. Using a relatively large photon bunch length with a full width at half maximum of 650 ps, the precessional motion of the magnetization was resolved up to frequencies of 2.5 GHz, thereby enabling sampling at frequencies significantly above the inverse bunch length. By simulating the experimental data with a numerical model based on a forced harmonic oscillator, we obtain good correlation between the two. The model, which includes timing jitter analysis, is used to predict the accessible frequency range of x-ray detected ferromagnetic resonance. [ABSTRACT FROM AUTHOR]

It is common to find a thin (∼0.5 nm) layer of Mg deposited prior to the MgO tunnel barrier in crystalline CoFe(B)/MgO/CoFe(B) magnetic tunnel junctions, due to the improved device performance that results. However, despite their common usage, the reasons why such layers are effective are unclear. We use structures that model the lower electrode of such devices to show that a suitably thick Mg insert layer enhances the crystal quality of both MgO and CoFe(B), permits interfacial oxides to reduce back to a metallic ferromagnetic state, and hence improves magnetic switching of the CoFe(B) electrode, properties which are inextricably linked to device performance. [ABSTRACT FROM AUTHOR]

We have studied the effect of annealing on the interface magnetization in a CoFeB/MgO structure which models the lower electrode in a magnetic tunnel junction device. We find that MgO deposition causes Fe to diffuse toward the CoFeB/MgO interface, where it preferentially bonds with oxygen to form a Fe-O-rich interfacial region with reduced magnetization. After annealing at 375 °C the compositional inhomogeneity remains; Fe is reduced back to a ferromagnetic metallic state and the full interfacial magnetization is regained. [ABSTRACT FROM AUTHOR]

An in-plane vectorial analysis of the magnetization of thin magnetic films is presented. Longitudinal soft x-ray resonant magnetic reflectivity curves display characteristic nodes where the longitudinal scattering component is suppressed by x-ray interference. The transverse magnetic component can be effectively retrieved at these nodal points, despite the use of circular polarization and longitudinal scattering geometry. Using a single geometric configuration, transverse and longitudinal magnetic hysteresis loops can be clearly separated. Calculations based on a Stoner–Wohlfarth model satisfactorily describe both loops. Therefore, this method presents a viable alternative to standard vectorial analysis techniques, with the additional benefit of element specificity. [ABSTRACT FROM AUTHOR]

The third international workshop on hard X-ray photoelectron spectroscopy (HAXPES 2009) was held at Brookhaven National Laboratory, Upton, New York, from May 20-22, 2009. This three-day workshop brought together approximately 100 scientists from 14 countries to discuss progress and future prospects for this rapidly developing field of research. The conference was sponsored by the National Synchrotron Light Source, the National Synchrotron Light Source-II Project, Brookhaven National Laboratory Condensed Matter Physics and Materials Science Department, and the National Institute of Standards and Technology. [ABSTRACT FROM AUTHOR]

Surface structural effects accompanying the antiferromagnetic-ferromagnetic magnetostructral transition of epitaxial FeRh thin films were investigated by grazing incidence x-ray scattering. Measurement of the film lattice parameters and variation of x-ray incident angles allow observation of the transition character on scales ranging from a few nm to the total through-thickness of the film. Out-of-plane lattice measurements confirm that the ferromagnetic phase nucleates from the surface during the heating process and is retained at the surface below the transition temperature during the cooling process. These results suggest that surface strain relief fosters nucleation of the ferromagnetic phase. [ABSTRACT FROM AUTHOR]

Single dusting layers of size-selected Co nanoclusters (NCs) of sizes ranging from 1.5–5.5 nm have been deposited by a gas-phase aggregation method in ultrahigh vacuum, and embedded within a NiFe matrix. Magnetic hysteresis loops have been obtained using soft x-ray magnetic circular dichroism, which shows that these Co NCs embedded in NiFe exhibit room temperature ferromagnetism with identical coercivity to the surrounding NiFe film. The strong local exchange field at the interface between NiFe and Co NCs, combined with the magnetic anisotropy of the NiFe film, allows stabilization of NC ferromagnetism which persists to room temperature. [ABSTRACT FROM AUTHOR]

We have studied the reversal of the bulk and interfacial magnetizations of the free layer of a spin valve using soft x-ray resonant magnetic scattering. By dusting the interface of the NiFe free layer with a few angströms of Co, we were able to distinguish between the interfacial and bulk magnetisms by tuning the x-ray photon energy. We measured hysteresis loops of reflected x-ray intensity at selected points in reciprocal space. We find no difference in the switching fields, showing that in transition metal ferromagnets, the exchange interactions are sufficiently strong to prevent a separate interfacial coercivity from arising. [ABSTRACT FROM AUTHOR]

The authors report on the use of a Co/Pt multilayer, which exhibits strong perpendicular magnetic anisotropy, to magnetostatically imprint a domain pattern onto a 50 Å thick Permalloy layer. Element specific soft x-ray magnetic scattering experiments were then performed so as to be sensitive to the magnetic structure of the Permalloy only. Off-specular magnetic satellite peaks, corresponding to a periodic domain stripe width of 270 nm, were observed, confirmed by magnetic force microscopy and micromagnetic modeling. Thus the authors have exploited the element specificity of soft x-ray scattering to discern the purely magnetic correlations in a structurally flat Permalloy film. [ABSTRACT FROM AUTHOR]

Fe ions of dose 5×1016 cm-2 were implanted at 200 keV into a-plane ZnO epitaxial films. The epitaxial quality of the postannealed samples was verified by x-ray diffraction ω-rocking curves and φ scans, whereas x-ray absorption spectroscopy identified the presence of both Fe2+ and Fe3+ ions, as well as changes in their relative concentration during postannealing. Superconducting quantum interference device measurements show that the as-implanted and postannealed films are ferromagnetic at room temperature. The saturation magnetization reduces during annealing possibly due to the decrease in the number of oxygen vacancies. [ABSTRACT FROM AUTHOR]

We report the results of soft x-ray resonant magnetic scattering experiments conducted on Co/Ru magnetic multilayers patterned into a reflection grating. Sample magnetization dependent scans of the in-plane wave vector transfer were performed to probe the relationship between the lateral physical and magnetic structures. Different Fourier components were found to dominate the sum and difference of these spectra, corresponding to different lateral wave forms for the structure-structure and structure-magnetism correlations. [ABSTRACT FROM AUTHOR]

A mode matching (MM)/finite element method (FEM) for the analysis of waveguide discontinuities is presented. The hybrid approach described combines the computational efficiency of the modal analysis with the versatility and flexibility of FEM and enables us to accurately model arbitrary cross section waveguides, where modal expansions cannot be derived analytically. The proposed procedure is based on the edge element expansion of the transverse field components for the direct calculation of the coupling integrals involved in the MM formulation. Numerical and experimental results are presented to show the validity and the accuracy of the method [ABSTRACT FROM PUBLISHER]

We present transmission-mode XMCD characterization of Fe, Ni, and Tb moment alignment in Tb-doped Ni81Fe19 thin films. The use of transmission geometry measurements has allowed the extraction of absolute projected elemental moments in the alloy. A very low projected Tb moment at 6% doping level, which nonetheless reverses with low applied fields (40 Oe), indicates a sperimagnetic alignment with respect to the Fe and Ni elements in the cosputtered polycrystalline alloy. [ABSTRACT FROM AUTHOR]