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The typical experimental conditions inside a transmission electron microscope (TEM), such as ultra-high vacuum, high-energy electron irradiation, and surface effects of ultrathin TEM specimens, can be the origin of unexpected microstructural changes compared with that of bulk material during in situ thermal-annealing experiments. In this paper, we report on the microstructural changes of a Fe–15%Si alloy during in situ TEM annealing, where, in its bulk form, it exhibits an ordering transformation from D03 to B2 at 650 °C. Using a heating-pot type double tilt holder with a proportional–integral–differential control system, we observed the precipitation of α-Fe both at the sample surface and inside the sample. Surface precipitates formed via surface diffusion are markedly large, several tens of nm, whereas precipitates inside the specimen, which are surrounded by Fe-poor regions, reach a maximum size of 20 nm. This unexpected microstructural evolution could be attributed to vacancies on Si sites, which are induced due to high-energy electron irradiation before heating, as well as enhanced thermal diffusion of Fe atoms. [ABSTRACT FROM AUTHOR]

The intermetallic compound Fe 1 − x Co x Si has a helical magnetic order for 0.05 < x < 0.8 , whereas its orbital angular momentum contributing to the occurrence of a Dzyaloshinskii–Moriya interaction has not yet been verified. We applied soft x-ray magnetic circular dichroism spectroscopy on the Fe L 2 , 3 and Co L 2 , 3 edges below T c for Fe 0.75 Co 0.25 Si such that their orbital magnetic moments m orb were evaluated independently. The dichroic signals provide direct experimental evidence that m orb for both Fe and Co is coupled in a parallel manner with each spin counterpart m spin . The ratio of m orb to m spin is independently estimated as m orb / m spin ∼ 3 % for Fe and 9% for Co. By comparing the average of the two m spin values with the saturated magnetization using a commercial superconducting quantum interference device (SQUID) magnetometer, the hole number in the d bands for both Fe and Co is roughly estimated as approximately 1.5. This suggests that Fe and Co should be arranged closely for stabilizing the ferromagnetic moments. [ABSTRACT FROM AUTHOR]

Atom probe tomography and secondary ion mass spectrometry were used to investigate the effects of carbon (C) co-implantation and subsequent annealing at 600 to 1200 °C on the behavior of implanted boron (B) atoms in silicon. When B alone was implanted, annealing at 600 to 800 °C caused it to form clusters in the peak region (1020 cm−3) of the concentration profile, and diffusion only occurred in the low-concentration tail region (<1018 cm−3), which is thought to be the well-known transient enhanced diffusion. However, when co-implantation with C was performed, this diffusion was almost completely suppressed in the same annealing temperature range. In the absence of C implantation, annealing at 1000 °C caused B clusters to begin to dissolve and B to diffuse out of the peak concentration region. However, this diffusion was also suppressed by C implantation because C atoms trapped B atoms in the kink region found at the B concentration level of 2 × 1019 cm−3. At 1200 °C, B clusters were totally dissolved and a strong B diffusion occurred. In contrast to lower annealing temperatures, this diffusion was actually enhanced by C implantation. It is believed that Si interstitials play an important role in the interaction between B and C. This kind of comprehensive investigation yields important information for optimizing ion implantation and annealing processes. [ABSTRACT FROM AUTHOR]

The single crystal of a chiral magnet Cr1/3NbS2 exhibits discrete changes in magnetization (M) in response to changes in magnetic field (H) triggered by the formation of a chiral soliton lattice (CSL). In order to provide evidence of this phenomenon, the study of the size effect is indispensable. We investigated the effects of size on this phenomenon by the use of two single crystals, (A) and (B), whose crystal sizes along the c-axis were 110 µm and 60 µm, respectively. First, in (A), the large jumps of M observed in the process of decreasing H exhibited inconsistent features, whereas the largest and second-largest jumps in (B) exhibited reproducibility for both the value of H and the magnitude of the M jumps. This confirms that these large jumps do not originate from the Barkhausen effect, as this effect would result in M jumps appearing at random values of H. When the system size of a sample becomes smaller, the features of the Barkhausen effect are suppressed. Second, as for the successive jumps observed in the H region where the rapid change in M is entirely seen for both the samples, the number of observed M jumps for (B) is more than that for (A). Indeed, the number of the domain wall due to the 2π-soliton in the CSL increases, as the c-axis length of the single crystal increases. However, a series of M jumps must appear in a limited H region below the critical field of the order of 2 kOe. The greater the number of M jumps, the more difficult the detection of the M jump will be in the H resolution of the present setup. Thus, the effects of size on the M jumps observed in the present setup can be understood within the framework of the CSL formation. [ABSTRACT FROM AUTHOR]

We perform structural analysis experiments on the chiral magnet Cr1/3NbS2, in which Cr3+ ions are inserted between hexagonal NbS2 layers. The noncentrosymmetrical nature of the inserted Cr3+ appears as a distorted CrS6 octahedron. Under the application of hydrostatic pressure, the lattice shrinks significantly along the c-axis rather than the a-axis. However, at a pressure P of approximately 3-4 GPa, a kink in the rate of decrease in the lattice parameters is observed, and the slight movement of a Nb atom along the c-axis brings about a decrease in the distortion of the CrS6 octahedron. This structural change qualitatively suggests a decrease in the strength of the Dzyaloshinskii-Moriya (D-M) interaction. Under hydrostatic pressure, the magnetic ordering temperature TC decreases, and dTC/dP exhibits a slight change at around 3 GPa. A series of experiments indicates that the change in the structural symmetry of the CrS6 octahedron influences the exchange network between Cr3+ ions as well as the D-M interaction. [ABSTRACT FROM AUTHOR]

The dependence of chemical composition on the average sizes of subnanometer-scale intrinsic structural open spaces surrounded by glass random networks in two-component silica-based glasses was investigated systematically using positronium (Ps) confined in the open spaces. The average sizes of the open spaces for SiO2-B2O3 and SiO2-GeO2 glasses are only slightly dependent on the chemical compositions because the B2O3 and GeO2 are glass network formers that are incorporated into the glass network of the base SiO2. However, the open space sizes for all SiO2-R2O (R=Li, Na, K) glasses, where R2O is a glass network modifier that occupies the open spaces, decrease rapidly with an increase in the R2O concentration. Despite the large difference in the ionic radii of the alkali metal (R) atoms, the open space sizes decrease similarly for all the alkali metal atoms studied. This dependence of the chemical composition on the open space sizes in SiO2-R2O observed by Ps shows that the alkali metal atoms do not randomly occupy the structural open spaces, but filling of the open spaces by R2O proceeds selectively from the larger to the smaller open spaces as the R2O concentrations are increased. [ABSTRACT FROM AUTHOR]

The temperature- and field-induced magnetic phase transitions are studied on textured samples of the pseudoternary Tb(sub 1-x)Y(sub x)Mn(sub 2)X(sub 2) systems by magnetization and thermal expansion measurements. The results show that the f-d exchange interaction is the primary factor governing the value of the transition temperature for the Tb subsystem T(sub C)(super Tb).

Positron annihilation spectroscopy is employed to estimate the size of subnanometer-scale open spaces in insulating materials. In most cases, the size is estimated from the lifetime of long-lived ortho-positronium (o-Ps) by pickoff annihilation using a simplified model. However, reactions of Ps with surrounding electrons other than the pickoff reaction, such as spin conversion or chemical reaction, could give a substantially underestimated size using the simplified model. In the present paper, we report that the size of the open spaces can be evaluated correctly by the angular correlation of positron annihilation radiation (ACAR) with a magnetic field using the spin-polarization effect on Ps formation, even if such reactions of Ps occur in the material. This method is applied to the subnanometer-scale structural open spaces of silica-based glass doped with Fe. We demonstrate the influence of the Ps reaction on size-estimation of the open spaces from the o-Ps lifetime. Furthermore, the type of reaction, whether spin conversion or chemical, is distinguished from the magnetic field dependence of the Ps self-annihilation component intensity in the ACAR spectra. The Ps reaction in silica-based glass doped with Fe is a chemical reaction (most likely oxidation) rather than spin conversion, with Fe ions. The chemical quenching rate with Fe ions is determined from the dependence of the o-Ps lifetime on the Fe content. [ABSTRACT FROM AUTHOR]

Sixty-degrees bent defect waveguides (DWGs) in an AlGaAs-based air-bridge-type slab was fabricated. The resulting optical transmission spectra were measured in the wavelength range between 850 and 1100nm.

We investigated complex magnetic domain formation on a chiral molecule-based magnet, [Cr(CN)6][Mn(R)-pnH(H2O)](H2O) (termed as R-GN), whose two-dimensional molecular network was constructed with the help of a single-handed chiral ligand ((R)-pn). There, the first- and third-harmonic magnetic responses (M1ω and M3ω) against the ac magnetic field were observed, and magnetic hysteresis in ac field of a few Oe was discussed in terms of Rayleigh loop. The diagnostics of this magnetic hysteresis clarified the complex process of magnetic domain formation against a change in temperature. For R-GN, it was reported that a giant M3ω (termed #4 in this paper) appeared just above the so-called 'magnetic ordering temperature (TC).' In the present study, three M3ω responses (#1-3) were newly observed on the lower-temperature side of #4, and the ac field dependencies for all of #1-#4 were investigated. #1 also accompanied the giant M3ω, which suggests that a significant degree of magnetic fluctuation surviving below TC. This glassy behavior below TC is an attractive new phenomenon in molecule-based magnets with a single-handed chiral ligand. #2 and #3 exhibited magnetic ordering and the formation of a small magnetic domain, respectively. The M3ω responses of #1-3 were suppressed with increasing the amplitude of ac field, and the corresponding magnetic hysteresis was a normal Rayleigh loop accompanying the out-of-phase of the M1ω response. The M3ω response of #4 without the out-of-phase of M1ω was, however, enhanced with increasing the amplitude of ac field, and #4 represented a large magnetic hysteresis in the paramagnetic region, intrinsically different from those of #1-#3. [ABSTRACT FROM AUTHOR]

We prepared polycrystalline In2O3–ZnO films by post annealing the amorphous films (1.0 wt % ZnO) at 200 °C with various annealing times ta 0≤ta≤20 h. We have measured the electric resistivity and Hall mobility and also observed film structures by not only the x-ray diffraction but also scanning transmission electron microscopy (STEM) with electron energy-loss spectroscopy (EELS). We have found the following: (1) Hall mobility takes the maximum with respect to the carrier density and the annealed films clearly show the superconductivity of which transition temperature increases with increase in ta. (2) The data on EELS spectra mapping of indium plasmon indicate that droplets of the pure indium phase exist on grain boundaries and near the interface between the film and the glass substrate. However, it seems that these droplets do not form an electrical conducting path but contribute to the scattering centers for carrier electrons, from the dispersed distribution of these droplets in STEM-EELS spectra mapping and the relationship between the electron mean free path and the grain size. [ABSTRACT FROM AUTHOR]

Electron emission properties of Spindt-type platinum field emission cathodes were investigated. The current–voltage characteristics together with the current fluctuation during long term operation were evaluated in ultrahigh vacuum. The changes of the emission properties in hydrogen, oxygen or carbon monoxide gas ambient were also investigated. Significant improvement of the emission properties was found when the cathode was operated in carbon monoxide ambient under a certain condition. It was found that the effect of the improvement lasted at least 200 h, and resistance against the oxygen exposure was also improved. The changes of the electron emission properties during long term operation in ultrahigh vacuum and in gas ambient were analyzed with the Seppen–Katamuki chart, of which ordinate and abscissa are slope and intercept of Fowler–Nordheim plot. The electron emission properties were distributed along a straight line in the Seppen–Katamuki chart, and those of the cathode improved by carbon monoxide exposure were distributed along another line. The deviation of the electron emission property in ultrahigh vacuum was considered to be due to change in the geometry of the emitting surface. The major reason for the modification of electron emission properties in carbon monoxide ambient was considered to be deposition of carbon onto the emitting surface, resulting in reduction of the work function. From the deviation of the Fowler–Nordheim characteristics in the Seppen–Katamuki chart, we presented an empirical equation for field emission. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We studied photoluminescence of Er in strained Si on a SiGe layer (Si:Er:O/SiGe) and unstrained Si on a Si layer (Si:Er:O/Si) grown by molecular beam epitaxy. Er-related photoluminescence was observed in both Si:Er:O/SiGe and Si:Er:O/Si samples. The peak intensity of Si:Er:O/SiGe at 1.54 µm was higher than that of Si:Er:O/Si. Moreover, the spectrum of strained Si (Si:Er:O/SiGe) was much broader than that of unstrained Si (Si:Er:O/Si). These differences between Si:Er:O/SiGe and Si:Er:O/Si suggest that the optical activation of Er can be enhanced by the presence of strain. [ABSTRACT FROM AUTHOR]

An observation of light propagation in a two-dimensional photonic crystal-based (2D-PC) optical waveguide is reported. Bent waveguides with a bending angle of 60° embedded in a 2D-PC triangular lattice with air columns were fabricated on a molecular-beam epitaxially grown AlGaAs/GaAs structure. The light-propagation characteristics were examined by observing scattered light from PC regions with incident light in the 850-950 nm range under an optical microscope using a charge coupled device camera. The incident light was strongly guided for wavelengths corresponding to the photonic band gap. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Several analyses are conducted to explain the synthesis, transport properties and the microstructures of the polycrystalline [In.sub.2][O.sub.3]- ZnO thin films. Electric resistivity and the Hall mobility of the films are also determined.

Provides information on a study which detailed the metalorganic molecular beam epitaxy growth characteristics of GaAs using triethylgallium and trisdimethylaminoarsenic by using reflection high energy electron diffraction intensity oscillations. Factor similar to the GaAs growth rate variation with substrate temperature; Reason for the desire for the development of metalorganic arsenic precursors as alternatives; Limitation in the growth of GaAs in metalorganic molecular beam epitaxy.

Presents a study which compared bismuth-system 2223 and 2212 thick superconducting tapes for grain alignment, current density and strain effects. Experimental details; Results and discussion; Conclusion.

Presents information on a study which characterized modulation-doped In[suby]Al[sub1-y]As/In[subx]Ga[sub1-x]As heterostructures grown on InP substrates by molecular beam epitaxy. Growth conditions of the heterostructures; Surface morphology; Hall measurement and discussion; Conclusions.

Presents a study that examined the sintering of bismuth-strontium-calcium-copper-oxide superconductors. Methodology; Analysis of the microstructure of the superconductors; Examination of the metallurgical properties of the samples.

The temperature- and field-induced magnetic phase transitions in pseudoternary systems Tb[SUB1-x]Y[SUBx]Mn[SUB2]Ge[SUB2] and Tb[SUB1-x]Y[SUBx]Mn[SUB2]Si[SUB2], which are characterized by a separate magnetic ordering of the Mn and Tb subsystems, have been studied on strongly textured samples by magnetization and thermal expansion measurements. In the concentration region 0.4&les;x&les;1.0, where the Mn moments are ordered only, the magnetic structure is antiferromagnetic. The magnetic ordering in the Tb subsystem is accompanied by a transformation of the Mn magnetic structure. As a result, the compounds show a spontaneous magnetization. This transition is of a first-order type. In both systems the transition temperature for the Tb subsystem T[SUP(Tb),SUBC] decreases linearly with increasing Y concentration and goes to zero at about x = 0.40. Canted phases and field-induced first-order transitions into the collinear phase have been observed in both systems below this temperature. It is concluded that the f - d exchange interaction is the primary factor governing the value of T[SUP(Tb),SUBC]. [ABSTRACT FROM AUTHOR]

Sixty-degree-bent defect waveguides (DWGs) in an ALGaAs-based air-bridge-type two-dimensional photonic crystal (2D PC) slab were fabricated, and the resulting optical transmission spectra and the plan-view image of the optical beam propagating along the bent DWG were measured in the wavelength range between 850 and 1100 nm. Using the two output ports of the stripe waveguides, one aligned to and another offset from the output edge of the bent DWG, the guided mode specific to the DWG and the slab mode in the defect-free PC slab were experimentally observed with the same sample. These results were verified using the calculated band structure and transmission spectra. [ABSTRACT FROM AUTHOR]

Presents a study which described the fabrication of V[sub3]Si multifilamentary superconductor with high overall J[subc] using a modified bronze process. Fabrication process for V[sub3]Si multifilamentary wires; Advantage of silicon bronze in reducing the bronze volume; Conclusions.

Emphasizes that bonding temperature and ferrite crystal orientation dominate pseudogap formation. Characteristics of the metal-in-gap (MIG) head; Influence of the annealing temperature on the diffusion at the boundary; Dependence of the ripple amplitude on the crystal orientation of ferrite cores.

Describes the fabrication of Bi-(Pb)-Sr-Ca-Cu-O superconductor into tapes without sheathing and into multifilamentary wires and tapes with Ag sheathing. Changes in the density and thickness of the superconductor; Results of the x-ray diffraction analysis.

Presents a study that measured the time dependence of the secondary ion intensity in secondary ion mass spectroscopy analysis of insulating films. Schematic diagram of the process on the reduction of surface charging and its equivalent circuits; Relation between the ion intensity suppression ratio and the film thickness.

Presents a study that fabricated a SiO[sub2]/TiO[sub2] high-reflectivity dielectric multilayer mirror specifically suitable for ZnSe-based vertical cavity surface-emitting lasers (VCSEL) operating in the green-to-blue spectral region. Technical issues to be studied for realizing green-to-blue VCSEL; Optical pumped properties of the vertical cavity; Description of an electron-beam evaporation system with an optical pumping system.

Presents information on a study which discussed critical temperatures (T[subc]) and critical currents (I[subc]) under uniaxial tensile loading on multifilamentary Nb[sub3]Al wires fabricated by a composite diffusion process. Summary of the fabrication process; Comparison of the rates of T[subc] and I[subc] degradation; Description of the wire cross section of Nb[sub3]Al.

Deals with a study which investigated improvements in high-field superconducting performance of V[sub3]Ga by a two-stage reaction process. Preparation of the V[sub3]Ga specimens; Findings.

Presents a study which investigated surface charging by ion bombardment. Description of the charging condition used in the investigation; Findings on the nonlinear effect on the charging; Ion irradiation which enhances the charging.

Investigates the effect of negative ion bombardment, conductive film coating and conductive layers induced by sputtering on charge neutralization. Purpose of secondary ion mass spectrometry; Sample used in the study.

A molecule-based magnet [Cr(CN)6][Mn(R/S)-pnH(H2O)](H2O) (termed R/S-GN) is a chiral crystal without an inversion center and mirror reflection, and its structural network is constructed using a chiral ligand diaminopropane (R/S)-pn. In S-GN, multiple spectra of ESR were observed below the magnetic ordering temperature by Morgunov et al. [Phys. Rev. B 77, 184419 (2008)]. They concluded that the phenomenon at the high field side occurred because the incommensurate magnetic structure resulted in a length-controllable superlattice of domain walls (the so-called chiral soliton lattice, CSL) under a dc magnetic field H applied perpendicular to the magnetic chiral axis. However, there multiple spectra were observed even for H nearly parallel to the chiral axis, a-axis, and their interpretation is unreasonable. Thus, we conducted an X-band electron spin resonance (ESR) measurement of R-GN under conditions similar to those of their experiment and performed Fourier spectrum analyses for the data of R-GN as an approach of physical characterization. By using two Lorentz spectra, the main ESR spectra for H // a were reproduced, and furthermore two prominent periodic modes were found by spectrum analyses based on Fourier transform. Two characteristic periods, p1 and p2 (

The kinetics of the reduction of interstitial oxygen (Oi) due to the formation of thermal double donors (TDDs) upon heat treatment in an oxygen-rich Ge crystal were investigated at various temperatures. Specimens were prepared from a Ge crystal with oxygen at a concentration of 4-5 × 1017 cm-3 grown by a new Czochralski method and were heat-treated in the temperature range 300-500 °C. Shrinkage of a dissolved oxygen absorption peak at 855 cm-1 and simultaneous development of a thermal double donor peak at 780 cm-1 were observed by infrared absorption spectroscopy at room temperature. The formation of TDDs was also detected electrically. Reduction of dissolved oxygen concentration upon the heat treatments was kinetically analyzed. The activation energy of the reduction of Oi concentration was evaluated to be 1.7 and 2.0 eV in the early and prolonged stages of the heat treatment, respectively, close to that of Oi diffusion. From the results, TDD development process was indicated to be the merge reaction of Oi-Oi to form oxygen dimers (Odimer) in the early stage of the heat treatment and further enlargement of Odimer to TDDs by absorbing Oi in the prolonged stage of the heat treatment in accordance with the On-2NN model. [ABSTRACT FROM AUTHOR]

We report comparison of the interfacial sharpness characterization of germanium (Ge) isotopic multilayers between laser-assisted atom probe tomography (APT) and secondary ion mass spectrometry (SIMS). An alternating stack of 8-nm-thick naturally available Ge layers and 8-nm-thick isotopically enriched 70Ge layers was prepared on a Ge(100) substrate by molecular beam epitaxy. The APT mass spectra consist of clearly resolved peaks of five stable Ge isotopes (70Ge, 72Ge, 73Ge, 74Ge, and 76Ge). The degree of intermixing at the interfaces between adjacent layers was determined by APT to be around 0.8 ± 0.1 nm which was much sharper than that obtained by SIMS. [ABSTRACT FROM AUTHOR]

A procedure to obtain the semi-quantitative depth distribution of radiative recombination centers in silicon power devices has been developed using cross-sectional cathodoluminescence (CL) by considering the nonradiative recombination on the surface of devices. Sharp luminescent peaks at 1.018 eV (W or I1), 1.040 eV (X or I3), and 0.790 eV (C) and a broad band about 0.90-1.05 eV in addition to near-band-edge emission were observed in the n-drift layer of the electron-irradiated lifetime-controlled punch-through insulated gate bipolar transistors using cross-sectional CL measurements. The semi-quantitative depth distributions of X, W, and C centers were obtained by the procedure. Each had a maximum value at the midpoint of the n-drift region, although electrons conventionally used to control carrier lifetime in power devices penetrated the entire device. One of the possible mechanisms for these distributions is the interaction of the X, W, and C centers with other point-like defects and impurities near the surface and the interface. The minority carrier (hole) diffusion length and the reduced recombination velocity in the devices are also extracted by this procedure. [ABSTRACT FROM AUTHOR]

A correction to the article "'Magnetic Diagnostics Using the Third-Harmonic Magnetic Response for a Molecule-Based Magnet Networked by a Single Chiral Ligand," by M. Mito et al. that was published in 2012 is presented.

The single crystal of a chiral magnet Cr1/3NbS2 exhibits discrete changes in magnetization (M) in response to changes in magnetic field (H) triggered by the formation of a chiral soliton lattice (CSL). In order to provide evidence of this phenomenon, the study of the size effect is indispensable. We investigated the effects of size on this phenomenon by the use of two single crystals, (A) and (B), whose crystal sizes along the c-axis were 110 µm and 60 µm, respectively. First, in (A), the large jumps of M observed in the process of decreasing H exhibited inconsistent features, whereas the largest and second-largest jumps in (B) exhibited reproducibility for both the value of H and the magnitude of the M jumps. This confirms that these large jumps do not originate from the Barkhausen effect, as this effect would result in M jumps appearing at random values of H. When the system size of a sample becomes smaller, the features of the Barkhausen effect are suppressed. Second, as for the successive jumps observed in the H region where the rapid change in M is entirely seen for both the samples, the number of observed M jumps for (B) is more than that for (A). Indeed, the number of the domain wall due to the 2π-soliton in the CSL increases, as the c-axis length of the single crystal increases. However, a series of M jumps must appear in a limited H region below the critical field of the order of 2 kOe. The greater the number of M jumps, the more difficult the detection of the M jump will be in the H resolution of the present setup. Thus, the effects of size on the M jumps observed in the present setup can be understood within the framework of the CSL formation. [ABSTRACT FROM AUTHOR]

During the Ru deposition process for granular type perpendicular magnetic recording media, both a reduction in the Ru intermediate layer thickness and lowering of sputtering gas pressure were successfully achieved by focusing on a self-shadowing effect. Oblique-incidence sputtering with a 60° incident angle under an Ar gas pressure of 0.6 Pa yielded (1) columnar Ru grains with a growth direction of 30° from the film normal, (2) c-plane sheet texture by epitaxial growth on the Pt underlayer, and (3) a flat envelope of the surface and a deep gap at grain boundaries. This change in the Ru structure significantly contributes to reducing exchange coupling among magnetic grains, especially in the initial growth region in an overlying granular medium.