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authoren Abstractauthoren Structuring materials is one mechanism to influence the thermal conductivity and thus thermoelectric efficiency. In order to investigate the scattering of phonons in multilayer structures we developed a beam matching technique, which is based on the concept of individual phonons and their scattering at interfaces. One of the major goals is to efficiently determine the complex band structure of the bulk materials. The complex band structure is determined using selected k-points on a triangulated grid in the complex plane of wave vectors perpendicular to the interface. Matching the phonon modes at an interface is translated to a singular value problem. Its null-vectors provide the coupling coefficients of the phonon modes across the interface. Besides giving explicit access to the modes as they scatter at the interface, the technique provides the transfer matrices, that provide the transmission coefficient of any multilayer structure. The transmission coefficient, in turn, yields the phononic thermal conductance for coherent transport. The knowledge of the matched phonons forms the basis of investigating incoherent transport under the influence of phonon–phonon or impurity scattering.

We have investigated structural, optical, and electrical properties of MgZnO:(Al/Ga) thin films in dependence on Mg and Al/Ga concentrations. For this purpose, thin films with two perpendicular, lateral composition gradients, i.e., the Mg composition is varied in one direction whereas the Al/Ga concentration is varied in a perpendicular direction were grown at by pulsed-laser deposition (PLD) using a threefold segmented PLD target and 2-inch in diameter c-plane sapphire substrates. It has been found that compensation by intrinsic acceptors limits efficient doping to dopant concentrations of about . Further, the electrical data suggests, that the compensating defect is doubly chargeable hinting to the zinc vacancy as microscopic origin. Increasing the dopant concentration above leads to a degradation of electrical and structural properties.

The impact of dislocations on surface topology as well as on quantum well emission in c-plane, semipolar, and nonpolar InGaN/GaN heterostructures is being analyzed by micro-photoluminescence and white-light-interferometry. V-pits with (101) and (10) side facets are identified in a (102) semipolar heterostructure. Hillocks formed by spiral growth around screw dislocations change from hexagonal to triangular to rectangular shape in polar, semipolar, and nonpolar heterostructures, respectively, reflecting the symmetry of the individual surface. The emission in semipolar quantum wells, grown homoepitaxially on bulk GaN substrates, show dark stripes aligned with misfit dislocations. For (112) and (201) orientation, these dark stripes are perpendicular and parallel, respectively, to surface striation.

A series of samples consisting of alternating stripes of ZnO grown by molecular-beam epitaxy (MBE) and radio-frequency (rf) sputtered Ga-doped ZnO stripes was laterally microstructured with a self-aligned pattern transfer method. We measured as a function of temperature the Seebeck coefficient S and the electrical resistivity ρ in-plane of the samples with the transport direction perpendicular to the stripe direction. Throughout the series the bar width and hence the number of interfaces was kept constant, but the interface profile was varied yielding different interface lengths and geometries. The dependence of S, ρ and the power factor S2/ρ on the interface length at room temperature were simulated using an empirical network model and it was demonstrated that the macroscopic transport coefficients are very sensitive to the interface region and that even this rather simple modelling yields useful information about the interface region.

Perpendicular exchange bias (PEB) between [Co 0.3 nm/Pd 0.8 nm]5 multilayers and IrMn antiferromagnetic (AFM) layer is studied as functions of thickness of the interface layer and the AFM layer. It is found that increasing the thickness of a CoFe interface layer up to 2.1 nm could effectively improve the PEB. The achieved PEB field (Hbias) is more than 500 Oe. On the other hand, the coercivity (Hc) exhibits an opposite trend as a function of CoFe interface layer thickness, which might promote the integration of PEB structure with the perpendicular magnetic memory stack. It is also found that PEB is sensitive to the thickness of the AFM layer. The thickness window is only around 2 nm to achieve the largest Hbias. Moreover, for a very thin IrMn layer, a ferromagnetic nature is observed at low magnetic fields, which is likely owing to the net spins at the surface that might have been magnetized by the CoFe interface layer.

A lithography-independent method for achieving self-organized growth of silicon nanowires by means of a Chemical-Vapor-Deposition process is investigated using a nanoporous alumina template on a 〈100〉 oriented silicon substrate. The position of the nanowires is determined by the location of gold colloids, acting as catalysts, which are initially deposited at the bottom of the pores over large areas of the sample. The direction of growth is guided by the pore axis, which is perpendicular to the silicon substrate surface. Results from scanning and transmission electron microscopy are presented and discussed. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Magnetization reversal in patterned perpendicular anisotropic DyFeCo films was investigated using micromagnetic simulations. The model consists of a square film of dimension 1 μm × 1 μm × 50 nm and a circular hole of diameter 500 nm on the top surface, with depth varying from 0-30 nm. The results show that for shallower holes the coercivity decreases rapidly with the hole depth, but for the deeper holes, the coercivity in the hole region is much larger than in the land region. Further analysis indicates the variation in coercivity is due to the narrow transition region formed near the hole boundary where the magnetization has a tilted distribution determined mainly by the competition between anisotropy and exchange interactions. The simulation results are qualitatively consistent with our previous experimental outcome.

Possibility of development of micro-undulator utilizing perpendicular magnetic recording was explored by 2-D FEM simulation. In the simulation FePt and CoCr layer were compared as an appropriate recording layer of the undulator. Also variation of maximum field and THD with aspect ratio and gap height were simulated so that they should be optimized in a given thickness of recording layer. From both the simulation results and Bitter patterns recorded on FePt/Fe micro-undulator, the possibility of development of micro-undulator by utilizing perpendicular recording technique could be confirmed.

Synchrotron-radiation computed laminography (SRCL) is developed as a method for high-resolution three-dimensional (3D) imaging of regions of interest (ROIs) in all kinds of laterally extended devices. One of the application targets is the 3D X-ray inspection of microsystems. In comparison to computed tomography (CT), the method is based on the inclination of the tomographic axis with respect to the incident X-ray beam by a defined angle. With the microsystem aligned roughly perpendicular to the rotation axis, the integral X-ray transmission on the two-dimensional (2D) detector does not change exceedingly during the scan. In consequence, the integrity of laterally extended devices can be preserved, what distinguishes SRCL from CT where ROIs have to be destructively extracted (e.g. by cutting out a sample) before being imaged. The potential of the method for three-dimensional imaging of microsystem devices will be demonstrated by examples of flip-chip bonded and wire-bonded devices.

The magnetic microstructure of high-coercivity sintered SmCo5 permanent magnets was studied with the conventional Bitter pattern technique, and also for the first time with the colloid-scanning electron microscopy (colloid-SEM) method. Both techniques were supported by digital image acquisition, enhancement and analysis. Thanks to this, it was possible to obtain high-contrast and clear images of the magnetic microstructure and to analyze them in detail, and consequently also to achieve improvements over earlier results. In the thermally demagnetized state the grains were composed of magnetic domains. On the surface perpendicular to the alignment axis, the main domains forming a maze pattern and surface reverse spikes were observed. Investigations on the surface parallel to the alignment axis, especially by the colloid-SEM technique, provided a detailed insight into the orientation of grains. The alignment of grains was good, but certainly not perfect; there were also strongly misaligned grains, although generally very rare. In most cases the domain structures within grains were independent of their neighbors, but in some cases (not so rare) the domain walls were observed to continue through the grain boundaries, indicating significant magnetostatic interaction between neighboring grains. Studies of the behavior of the magnetic microstructure under the influence of an external magnetic field, performed for the first time on the surface parallel to the alignment axis (with the conventional Bitter pattern method), showed that the domain walls move easily within the grains and that the magnetization reversal mechanism is mainly related to the nucleation and growth of reverse domains, i.e. that sintered SmCo5 magnets are nucleation-dominated systems. Groupwise magnetization reversal of adjacent magnetically coupled grains was observed, an unfavorable effect for high-coercivity magnets. Images obtained by the colloid-SEM technique and the conventional Bitter pattern method were compared and some aspects related to the observation of magnetic microstructures by these two techniques were also discussed. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Martensitic transformations and characteristics of the magnetic-field-induced strain (MFIS) on a nearly stoichiometric Ni51Mn25.5Ga23.5 single crystal have systematically been investigated by various methods, such as ac magnetic susceptibility, resistance, strain measurements and metallographic observations. A large spontaneous strain of 1.62% corresponding to a two-way thermoelastic shape memory effect is obtained in the single crystal, which is attributed to the high level of oriented internal stress and the preferential orientation of the martensitic variants. When the sample is cooled in a dc magnetic field applied perpendicular to the measuring direction of strain, a large and reversible MFIS up to 1.5% is found. This value of 1.5% is approximately two times larger than that detected in zero field cooling. The results are discussed with respect to growth mechanism of single crystals and the shape memory characteristics. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The magnetic domain walls at the edges of a large patterned and exchange-biased NiO (10–60 nm)/NiFe (10 nm) bilayers and their motions with applied field were investigated by MFM. Three kinds of domain walls were found at the edges of the NiO (30 nm)/NiFe (10 nm) bilayer having the exchange biasing field (Hex) of 21 Oe. Two zigzag charged walls and Neel wall appeared at the edges perpendicular and parallel to Hex, respectively. The zigzag charged walls are nearly a factor of three wider than the Neel wall, and were not observed for the strong exchange-biased bilayer (60 nm NiO, Hex = 75 Oe). We investigated the subsequent motion of the walls, and identified the pinning and nucleation sites during magnetization reversal. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

GdCa4O(BO3)3 single crystals grown by the Czochralski technique were investigated by conventional transmission and back-reflection X-ray topography. The results were correlated with the growth conditions and stoichiometry of the crystals. Extended defects, especially dislocations, with different density, in samples cut perpendicular and parallel to the b-axis were investigated. Long, straight dislocations lying perpendicular to [100] and [010] directions were observed. Periodical, small fluctuations of the diameter induced some defects. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The process of making laterally graded interference filters has been reanalyzed. A simple and consistent picture arises if one applies a constant electric field perpendicular to the etch current instead of a constant current. The system is quantitatively modeled by means of a pure ohmic equivalent circuit model.

The structure of the room temperature phase αI-Cu2Te is studied by means of electron diffraction and high resolution electron microscopy. It is found that the structure is the result of two modulations. The first one is the periodic introduction of planar translation interfaces perpendicular to the [111]c direction of the fcc basic structure. The second one is the ordering of Cu in octahedral and tetrahedral sites, in a way similar to that known for the β-Cu2Se structure. The superstructure unit cell includes twelve Te layers. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We describe domain walls in ultrathin magnetic films with spatially varying uniaxial anisotropy. By virtue of minimization of the total energy functional we obtain the corresponding domain wall profiles. The two-levels anisotropy modulation with the change of the anisotropy constant (K) sign leads to the transition between the perpendicular and the in-plane magnetization states through the appearance of 90° domain walls. The existence of 180° and 0° domain walls with plateaus in the middle region is shown for a cosine-like anisotropy modulation. The domain wall profiles are tunable by a proper choice of geometrical parameters of the K-modulation.

We studied the structure and magnetic properties of molecular-beam epitaxy grown 300 A thick Fe/Pt multilayers with different bilayers thickness and annealing temperature. The Fe/Pt multilayers were deposited on 100 A thick Pt buffer layers at 100 °C on Al 2 O 3 (0001) substrates. The structure of as-deposited Fe/Pt films was fcc(111). While the post annealing temperature ≥400 °C, additional Fe(110) and FePt(100) orientations were observed and the intermixing between Pt buffer layers and Fe/Pt multilayers started. A large coercivity range, namely, 200 Oe to 1.6 Tesla can be tuned by varying the bilayers thickness and annealing temperature. The perpendicular magnetic anisotropic constant reached 3.5 x 10 7 erg/cm 3 after 600 °C post annealing.

The influence of intermediate layer characteristics on the structural and magnetic properties of CoCr-based perpendicular media has been investigated. CoCrPt-SiO 2 stacks were deposited on a 2.5-inch glass substrates. To improve intermediate layer properties without noticeable sacrifice of magnetic and structural properties of recording layer, the conditions of intermediate layer deposition were varied. The recording layer was deposited on the Ru intermediate layer in 20 mTorr Ar pressure to increase coercivity. As a result, coercivity is increased from 2.2 to 3.7 kOe because the interface between Ru intermediate layer and recording layer was rougher than the interface formed at low Ar pressure. Additionally, to increase perpendicular anisotropy of recording layer, the Ru sputtering temperature condition was varied, ranging from 150 °C to 300 °C. However, the perpendicular anisotropy of recording layer was decreased.

To reduce the core loss of grain oriented silicon steel, various metallurgical attempts have been made. The laser scribing reduces the core loss of 3% Si-Fe, because sub-domains induced by scribing produce many active domain walls which reduce the eddy current loss. The profiles of ac hysteresis loop and core loss have been measured for samples oriented parallel and perpendicular to the [001] axis in (110)[001] grains of 3% Si-Fe before and after laser scribing. The observed ac hysteresis loop profiles have been analyzed in terms of domain reorientation under field. For the parallel and perpendicular samples, the reductions of core loss are 5.7% and 30.3% by laser scribing at the magnetic induction 1.3 T and magnetizing frequency 60 Hz.

In perpendicular recording, double layered media with soft underlayer (SUL) are outstanding in view of increasing writing head field and the head field gradient. However, the SUL could serve as various noise sources. In order to investigate the effect of SUL on noise, writing and reading processes in a perpendicular system including a single pole head and a recording medium with the SUL were performed by micromagnetic simulation. It was found that when an abrupt head field is applied, the SNR of the double layered medium shows much lower SNR compared with the single layered medium. The higher noise in the double layered medium is not associated with transition jitter but with transition position shift. The transition position shift is associated with change of magnetization pattern of the SUL with time during writing process. In the present paper, we discuss the change of magnetization patterns of the SUL with time, for two different head sizes.

Magnetic force microscopy (MFM) analyses were done to investigate the magnetization reversal behaviour of a perpendicular patterned CoCrPt medium. The medium was observed by using in-situ (in the presence of perpendicular field up to 5.5 kOe) and ex-situ (in the absence of external field) MFM techniques. Magnetization state, coercivity and magnetostatic energy of the individual magnetic dots were studied in a given microscopic area. Taking account of the magnetostatic energy for the respective nanomagnets, the maps of the experimental and intrinsic coercivities for this region were obtained.

In 1996, Berger and Slonczewski independently predicted that a large enough spin-polarized dc current density sent perpendicularly through a ferromagnetic layer could produce magnetic excitations (spin-waves) or reversal of magnetization (switching). In the past few years, both current-driven switching and current-driven excitation of spin-waves have been observed. The switching is of potential technological interest for direct 'writing' of magnetic random access memory (MRAM) or magnetic media. The spin-wave generation could provide a new source of dc generated microwave radiation. We describe what has been learned experimentally about these two related phenomena, and some models being tested to explain these observations., 5 pages, 7 figures, expected to appear in conf. proceedings

Magnetic force microscopy (MFM) was used to investigate the domain structure of sintered Nd–Fe–B and SmCo5 permanent magnets at the surfaces perpendicular to the alignment axis. The studied magnets had average grain sizes of about 10 μm and 20 μm, respectively. The observed domain structures resembled those present in bulk uniaxial crystals with strong magnetocrystalline anisotropy. Nevertheless, the main domains in the Nd–Fe–B magnets were approximately three times smaller than those in the SmCo5 magnets. The differences in the domain structures were attributed to different values of the relative magnetic anisotropy as well as to different grain sizes for the two mentioned types of magnets. A comparison was made between theoretical and experimentally determined values of the domain width. The effect of tip-specimen distance on the MFM image was demonstrated and explained. The magnetic images were correlated with the surface topography revealed by atomic force microscopy (AFM). (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Transmission electron microscopy (TEM) observation was performed for microstructure in epitaxial lateral overgrown (ELO) GaN layers with attention to the behavior of horizontal dislocations (HDs). The ELO-GaN layers were grown by metalorganic vapor phase epitaxy (MOVPE). The facet planes of the ELO-GaN layer were controlled by the two-step ELO technique. In the specimen with a narrow mask-window of 3 μm, HDs were generated over the mask-window. In the case of a wider mask-window of 5 μm, HDs were generated also near the mask-edge. Plan-view TEM observation showed that HDs were formed in the shape of waves. The Burgers vector of the HDs was perpendicular to the mask-edge. From the curvature of HDs, the internal stress in the region over the mask-window of ELO-GaN was roughly estimated to be 0.01-0.04 GPa.

(a) Institute for Problems of Mechanical Engineering, Russian Academy of Sciences,Bolshoj 61, Vas. Ostrov, 199178 St. Petersburg, Russia(b) Institute of Physical Metallurgy, Freiberg University of Mining and Technology,Gustav-Zuener-Str. 5, 09596 Freiberg, Germany(c) Ioffe Physico-Technical Institute, Russian Academy of Sciences, Polytechnicheskaya 26,194021 St. Petersburg, Russia(Received August 27, 2001; in revised form March 1, 2002; accepted March 4, 2002)Subject classification: 61.72.Lk; 68.37.LpTransmission electron microscopy (TEM) images of disclination defects are modeled in the fra-mework of Howie–Whelan two-beam approach and by taking into account elastic distortionsassociated with the defects. Disclinations are generated in crystalline materials in the course ofplastic deformation and can be observed in the junctions of several grain or cell boundaries. Thelines of disclinations are assumed to be parallel or perpendicular to the free surfaces of a thinfoil. For such a geometry disclination elastic fields (e.g. displacements and stresses) in the foilinterior are constructed by applying the technique of “virtual” surface defects. The obtainedresults demonstrate the possibility to extract the disclination parameters from the data of TEMobservations.

Vapor deposited epitaxial films of quaterrylene on (001) of KCl were investigated using high-resolution electron microscopy and electron diffraction. The crystal c-axis is parallel and perpendicular to the substrate surface at a lower and at a higher temperature, respectively. This means that the long axis of the quaterrylene molecule is in the film plane at a lower temperature and becomes perpendicular to it at a higher temperature. High-resolution images revealed the detailed features of an edge dislocation, twin boundaries and small angle grain boundaries. Differing from the normal part of the crystal, the unit cells are deformed and the orientation of molecules are varied from unit cell to unit cell. In addition, solitary molecular columns are seen to occupy empty spaces formed at the dislocation core or at the grain boundaries in order to relax the lattice distortion.

The influence of the anisotropic in-plane strain on the optical response of GaN layers grown on a-plane sapphire is investigated. A splitting of the Γ 5 states of the A and B free excitons into two components, polarized parallel and perpendicular to the strain direction, is observed. The experimental results are discussed in the framework of the effective exciton Hamiltonian formalism.

Giant magneto-resistance (GMR) effect in a spin-valve has a uni-directional or cosine dependence when rotated in an applied magnetic field; however, anisotropy effects cause deviations from this cosine dependence. The influence of uniaxial anisotropy in the free layer and Anisotropic Magneto-Resistance (AMR) were studied on the angle dependent resistance changes in IrMn spin-valves. The uniaxial anisotropy component was analyzed by changing the anisotropy axis from parallel to perpendicular to the bias direction in different sample sets. The deviation due to AMR was determined by changing the current direction from parallel to perpendicular to the bias direction in separate rotation measurements. The results indicated that the uniaxial anisotropy had no influence on the angle dependent resistance change while AMR added a cosine-squared resistance signal to the overall resistance change. A discrepancy between experiment and theory of the AMR influence was seen with use of a simple simulation. Ferromagnetic interlayer coupling is identified as a possible cause for this difference between theory and experiment.

We introduce a phenomenological theory which gives a consistent method to calculate the distribution of induced anisotropy and the equilibrium magnetization within a magnetic layer as functions of the layer thickness, the material parameters and applied magnetic field. Within this theory the transition from the in-plane phase (larger thickness) to the perpendicular phase (thinner films) always occurs continuously via transformation into an intermediary (twisted) phase which is inhomogeneous across the layer thickness. The complex redistribution of the magnetization in the twisted phase accounts for the peculiarities of domain structures in the transitional regions of layered systems such as Cu/Ni/Cu(001) and Co/Au(111).

An extended method for anisotropy field measurements has been developed using a vector vibrating sample magnetometer (VSM). The technique, which relates the switching of particles nearly perpendicular to an applied field to the sample anisotropy, is suitable for magnetic media that contain orientated particles. Results measured as a function of angle are extrapolated to 90° for an improved measure of anisotropy field. In plane properties have been investigated for a series of four advanced double coated metal particle (MP) tapes. The results show that the in plane anisotropy field is related to the magnetic coating thickness, as a result of changes in magnetostatic interactions between the particles with thickness.

The effects of magnitude and angle of applied field and the effect of Gilbert damping constant on switching time of a cubic particle with crystalline anisotropy at 0 and 350 K were investigated by using numerical simulation. The switching time decreases with increasing angle of applied field at 0 and 350 K. The switching time is proportional to (1 + α 2 )/α, when applied field is a few per cent larger than the Stoner-Wohlfarth switching field, and it is not proportional to (1 + α 2 )/α when the applied field is close to the switching field. When the applied field is almost oriented in the -z direction, t s is proportinal to 1/((H/H s ) - 1). However, when the field is applied in the direction larger than a few degrees, t s is not proportional to 1/((H/H s ) - 1). Higher frequency than 1 GHz may be hard to be applied in perpendicular recording if the angle between the head field and the direction perpendicular to the film plane is smaller than a few degrees.

This paper presents a new method of applying stresses to an amorphous ring core. Due to the special cylindrical backings, compressive stress is applied perpendicular to the direction of flux density. In this method the distribution of stresses in the core is uniform and known. This method was used to investigate magnetoelastic properties of a ring core made of Fe 40 Ni 38 Mo 4 B 18 amorphous alloy. The changes of quasi-static hysteresis loops, flux density and permeability for compressive stresses up to 10 MPa are presented. Permeability at H m = 1.5H c decreases over 40% for stresses up to 10 MPa. These experimental results confirm that the presented method may be very useful in the construction of stress transducers.

Columnar ELOG growth domains formed in a 65 μm thick HVPE GaN layer during overgrowth of hexagonal SiO 2 masks are three-dimensionally characterized using spatially and spectrally resolved scanning cathodoluminescence (CL) microscopy. In conjunction with cross-sectional imaging perpendicular to the c-plane, a direct visualization of the 3D domain formation is achieved by consecutive vertical series of CL mappings parallel to the c-plane. A perfect agreement between the local luminescence properties and the evolution of the local free carrier concentration during the different stages of overgrowth is confirmed by micro-Raman measurements. While mask-periodic domains with specific optical and electronic properties are observed for initial growth, homogeneously high crystal quality at the sample surface is evidenced.

Single crystal PbWO 4 has been grown by the improved Bridgman method. The absorption spectra in polarized light of the sample with the crystal c-axis parallel to its surface have been measured. The absorption spectra of the as-grown crystal show a 350 nm weak band with dichroism in polarized light. Subtracting the polarized light absorption spectrum with the electric vector E parallel to the c-axis by that one with E perpendicular to the c-axis, the polarized light difference spectrum is obtained. The polarized light difference spectrum indicates that the 350 nm band has two peaks and can be decomposed into two bands peaking at 330 and 360 nm, respectively. In order to determine the detailed structure of the 350 nm band, annealing experiments in air condition of the as-grown crystal at different temperatures were performed Difference spectra of the annealed crystal have been obtained by subtracting the absorption spectra of the crystal annealed at different annealing temperatures by that one of the as-grown crystal. The absorption spectra features also indicate that the 350 nm absorption band is composed of two bands peaking at 330 and 360 nm, respectively. The annealing properties of the 330 nm and the 360 nm band are obviously different. We come to the conclusion that the 350 nm band is a composed band and can be decomposed into two bands peaking at 360 and 330 nm, respectively. The two bands are suggested to belong to different color centers.

Recent oblique-angle optical second harmonic generation (SHG) studies, using 1064 nm excitation, of the single-domain In-induced 4 × 1 reconstruction of vicinal Si(111) have been extended to normal incidence studies. The oblique incidence work had shown that the nonlinear susceptibility along the In chains increased by a factor of about 2.5 over that of the clean surface, while the change in susceptibility perpendicular to the chains was small. In contrast, the normal incidence studies show a small reduction in the nonlinear susceptibility in both directions, on formation of the In chains. The normal incidence SH response is consistent with recent reflection anisotropy spectroscopy (RAS) studies of the same system at near normal incidence. The oblique incidence SHG response provides additional information, inaccessible to linear optical probes, of the quasi-one-dimensional nature of the metallicity along the chains.

The paper theoretically investigates peculiarities of the carrier redistribution in periodic homogeneously doped semiconductor graded-band-gap multilayer structures with linear coordinate dependence of the energy gap which are caused by electric current in the direction perpendicular to the layers. It is shown that at strong electric fields a practically constant carrier concentration is set up in almost the whole volume of the structure except for the thin regions in the vicinity of the interfaces. In the case of asymmetric structures carrier redistribution can give rise to a change of the total number of carriers.

The conventional ellipsometry can be applied to determine the optical properties of anisotropic materials only if the measurements are made for in-plane uniaxial anisotropy of the bulk sample with the optic axis parallel or perpendicular to the plane of incidence. For arbitrarily oriented anisotropic materials, the generalized ellipsometry method should be used. The generalized fixed polarizer, rotating-polarizer and fixed analyzer spectroscopic ellipsometry was used. The method is experimentally verified for uniaxial mercuric iodide (HgI2). The normalized Jones matrix and the complex optical functions are extracted from the measured Fourier coefficients at different sample orientations and different polarizer and analyzer angles P and A.

Surface sensitive grazing incidence diffraction (GID) is used to study the interface between silicon and sapphire. A thin crystalline layer of aluminium silicate with a lateral lattice parameter slightly different from sapphire is found and quantified by model calculations. We demonstrate that in GID, very thin interface layers can be investigated for which the sensitivity for measuring small Bragg angle differences, Δθ, is enhanced by a factor of about 25 by the projection of Δθ into the plane perpendicular to the sample surface. The accuracy of the lattice parameter determination is thereby improved by at least one order of magnitude.

The energies of the intrinsic stacking fault in 20 tetrahedrally coordinated crystals, determined by electron microscopy from the widths of extended dislocations, range from a few mJ/m2 to 300 mJ/m2. The reduced stacking fault energy (RSFE: stacking fault energy per bond perpendicular to the fault plane) has been found to have correlations with the effective charge, the charge redistribution index of the crystals and with the c/ aratio of the wurtzite structure (for many of the diamond and zincblende crystals, the wurtzite structure has also been reported to exist as a metastable phase). The implication of the correlations has been discussed from the point of the relative stability of the crystals between the cubic structure and the hexagonal structure.

The thermal conductivity of LiKSO 4 crystals in the direction perpendicular to the sixfold axis was measured in the temperature range from 10 to 250 K. In the vicinity of 38 K anomalous changes in the thermal conductivity were observed. The decrease in thermal conductivity for T < 38 K is probably related to the appearance of antiphase domain walls formed as a result of the nonferroic phase transition at that temperature. This effect masks the influence of the ferroelastic domain walls on the thermal conductivity of the crystal studied.

Using torque magnetometry (TM), SQUID and TEM we have investigated a series of thin (50 to 80 nm) amorphous Tb O.28 Fe O.72 films. A different influence on the magnetic anisotropy by field annealing at 323 to 873 K with magnetic field either perpendicular or parallel to the sample surface is found. The pair-ordering mechanism is believed to be the source of perpendicular anisotropy in amorphous Fe-Tb films which corresponds to results from measurements of pair distribution functions (pdfs) by in-situ-TEM experiments. Unidirectional anisotropy was found in the sample plane which corresponds to the orientation of the external magnetic field during the annealing process. The magnetic (TM) and structural (TEM) results obtained suggest that the unidirectional anisotropy is due to the tilt of the easy axis from the film normal as a consequence of dual magnetron sputtering.

The magnetic properties of sputtered RE-TM(CoGd)/Pd multilayered films were studied. CoGd layers with high Gd concentration were amorphous. Reducing the Gd concentration, CoGd layers changed from amorphous to crystalline gradually. Like in the crystalline Co/Pd multilayered films, perpendicular magnetic anisotropy (PMA) was observed only for CoGd/Pd multilayered films with thin magnetic layer. It is interesting to note that the critical magnetic layer thickness, below which the easy magnetization axis is perpendicular to the film plane, reaches 2.5 nm for CoGd/Pd multilayered films with amorphous CoGd layers and is larger than that of Co/Pd multilayered films. The PMA energy density of CoGd layers was much higher than that of amorphous CoGd films. These results are discussed in terms of the perpendicular magnetization mechanism in amorphous CoGd films as well as of interface magnetic anisotropy.

The thickness dependence of magnetoresistance was studied for a series of thin Co 20 Ag 80 films. The room temperature magnetoresistance in perpendicular configuration (CIP) was measured for as-deposited and annealed samples in fields up to 2 T. All samples were annealed for 10 min at temperatures ranging from 423 to 623 K at steps of 100 K. MR values growing with the thickness t were observed. MR varies steeply for small t and saturates at larger thicknesses. Changes of the width of the MR curve with the film thickness were also analyzed.

In this paper we present a three-dimensional waveguide structure with unique optical and fluidic properties and demonstrate its application as a substrate for DNA microarrays. The structure is fabricated by thermal oxidation of a macroporous silicon membrane with a periodic pattern of discrete microchannels running perpendicular through the substrate. Partial oxidation generates compartments with channel walls that are completely converted into SiO2 but leaves a rectangular grid of silicon walls separating the SiO2 compartments. We demonstrate that the SiO2 walls act as optical waveguides and the opaque silicon walls divide the substrate into optically isolated compartments. In DNA microarray experiments, we show that the silicon walls of the compartments prevent cross talk between adjacent DNA spots. The structure is compatible with all conventional read-out techniques such as fluorescence, chemiluminescence, and precipitation staining. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The local elastic response of individual grains in lead-free Nb-doped Bi4Ti3O12 piezoelectric ceramics have been examined by atomic force microscopy in the acoustic mode. Subsurface features with different elasticity down to 60 nm are imaged from the cantilever deflection vibration at a modulation frequency much lower than the cantilever resonance. Local elastic regions parallel and perpendicular to the long axis of the plate-like grains are found in the Bi4Ti3O12 piezoelectric ceramics, which are most likely a result of the crystal structure arrangement undergone in the grain growth of the Nb-doped Bi4Ti3O12 piezoelectric ceramics during sintering. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The mechanical and electrical response of Pb (Mg1/3Nb2/3)- O3–PbTiO3 single crystals to micro-indentation are investigated using the newly developed low frequency scanning probe acoustic microscopy which is based on the atomic force microscope. There are three ways to release the stress produced by indentation. Plastic deformation emerged directly underneath the indentor and along the indentation diagonals. In addition, indentation-induced micro-cracks and new non-180° domain structures which are perpendicular to each other are also observed in the indented surface. Based on the experimental results, the relationship between the cracks and the domain patterns was discussed. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

A new approach is proposed for studying the diffraction intensity- distribution of the single crystals with nearly parallel dislocations. This approach can be directly applied on the realistic dislocation configurations in the crystals which can be made visible as etching-pits by proper etching procedures. The displacement field is estimated by the superposition of the displacements from all the dislocations. The diffraction behaviour on the plane which is perpendicular to those dislocations is determined by a Fourier transformation algorithms.

Magnetic garnet films of composition Y3–xBixFe5–yAlyO12 are grown by liquid phase epitaxy on [111] and [110] oriented substrates of gadolinium gallium garnet. They have high uniaxial anisotropy and support lattices of parallel stripe domains. The two branches DR+ and DR− of the domain resonance are excited by rf magnetic fields polarized in the film plane. Resonance frequencies of more than 7 GHz are observed; they are measured as function of a static induction B⟂ applied perpendicular to the film plane. With increasing B⟂ the resonance mode DR+ is confined to the small domain with equilibrium magnetization antiparallel to B⟂, while DR− is confined in the larger stripe having equilibrium magnetization parallel to B⟂. At the collapse induction the DR− mode merges into the ferrimagnetic resonance. The resonance modes DR± are calculated using a new method to determine the demagnetizing energy. Excellent agreement between theory and experiment is obtained. Mittels Flussigphasen-Epitaxie werden magnetische Granatfilme der Zusammensetzung Y3–xBixFe5–yAlyO12 auf [111] und [110] orientierten Substraten aus Gadolinium-Galliumgranat (GGG) hergestellt. Die Filme sind durch eine hohe uniaxiale Anisotropie ausgezeichnet, und es bildet sich ein Gitter paralleler Streifendomanen aus. Die beiden Zweige, DR+ und DR−, der Domanenresonanz lassen sich durch Hochfrequenzfelder anregen, die in der Filmebene polarisiert sind. Die Resonanzfrequenzen liegen zum Teil uber 7 GHz; sie werden in Abhangigkeit von einer statischen Induktion B⟂ gemessen, die senkrecht zum Film anliegt. Mit steigender Induktion B⟂ kann die DR+-Mode der schmalen, zum Feld antiparallel magnetisierten Domane zugeordnet werden, wahrend die DR− in der breiteren, zum Feld parallel magnetisierten Domane dominiert. Bei der Kollapsinduktion geht die DR− in die ferrimagnetische Resonanz (FMR) uber. Die Resonanz-moden DR± werden mit Hilfe einer neuen Methode zur Bestimmung der Entmagnetisierungsenergie berechnet. Die Ubereinstimmung zwischen Theorie und Experiment ist ausgezeichnet.

We present the local Hall effect in a hybrid Hall device incorporating a micron-scaled InSb semiconductor cross junction and a single microstructured ferromagnetic element. A clear hysteresis loop was found to appear in the output signal for the cross junction with a ferromagnetic element due to the strong perpendicular component of the magnetic fringe field emanating from the edge of the ferromagnet. We demonstrate that the local fringe field from the ferromagnetic element inducing a Hall voltage improves the Hall sensitivity (4.5 Ω/Oe).