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Mn3Sn is an anomalous Hall effect (AHE) antiferromagnet that exhibits the hysteretic AHE in antiferromagnetic (AFM) phase at room temperature. We report that whisker Mn3Sn crystals grown by the flux method exhibit a non-hysteretic AHE at mid-to-low temperatures when the whisker Mn3Sn is surrounded by a thin layer of ferromagnetic Mn2−xSn. These crystals exhibit a hysteretic AHE above 275 K due to the spin alignment of the inverse triangular lattice, which is similar to other crystals. However, upon cooling the crystal, it exhibits a non-hysteretic AHE with a spiral AFM spin structure at 100–200 K. We concluded that the non-hysteretic AHE is induced at the interface of Mn2−xSn/Mn3Sn. We believe that the scalar-spin chirality in the spiral AFM phase of Mn3Sn, modulated by Mn2−xSn through the magnetic proximity effect, produces the AHE. This discovery opens a new avenue for tailoring the AHE by magnetic layers. [ABSTRACT FROM AUTHOR]

In this study, we developed a one-step method for fabricating hydrophobic surfaces on copper (Cu) substrates. Cuprous oxide (Cu2O) with low free energy was successfully formed after low-fluence laser direct irradiation. The formation of Cu2O enhanced the hydrophobicity of the Cu substrate surface, and the contact angle linearly increased with the proportion of Cu2O. The Cu2O fabricated by low-fluence laser treatment showed the same crystal plane orientation as the pristine Cu substrate, implying an epitaxial growth of Cu2O on a Cu substrate. [ABSTRACT FROM AUTHOR]

Ultrafast phenomena in gold nanotriangles (AuNTs) were investigated using a transient electron energy-loss spectroscopy (TEELS) technique under irradiation from a 150-fs pulse laser with a wavelength of 780 nm. This investigation was conducted using a time-resolved transmission electron microscopy method that was developed to measure the dynamics of nanomaterials. Enhancement of the intensity and energy-width broadening of the energy loss were observed at the EEL peaks associated with surface and bulk plasmons on the AuNTs. The TEELS measurement revealed two decay processes of 7.8 ps and longer than 100 ps that compensate for relaxation times of excited surface plasmons using transient absorption spectroscopy. The results show that the bulk and surface plasmons have the same time evolution, i.e., that the excited electrons on the surface and in the bulk have the same relaxation processes in both electron–phonon and phonon–phonon interactions. The time evolution of electronic and lattice temperatures was also estimated based on the measured relaxation time using a two-temperature model, which revealed the volume expansion of the AuNTs and clarified the energy shifts of plasmons. Details of excited electrons in nanoparticles investigated via plasmon energy loss are expected to facilitate improvement in the performance for energy harvesting of photons in nanostructure-controlled materials. [ABSTRACT FROM AUTHOR]

In this study, a noise-reduction technique for series low-dose electron holograms using tensor decomposition is demonstrated through simulation. We treated an entire dataset of the series holograms with Poisson noise as a third-order tensor, which is a stack of 2D holograms. The third-order tensor, which is decomposed into a core tensor and three factor matrices, is approximated as a lower-rank tensor using only noise-free principal components. This technique is applied to simulated holograms by assuming a p-n junction in a semiconductor sample. The peak signal-to-noise ratios of the holograms and the reconstructed phase maps have been improved significantly using tensor decomposition. Moreover, the proposed method was applied to a more practical situation of time-resolved in situ electron holography by considering a nonuniform fringe contrast and fringe drift relative to the sample. The accuracy and precision of the reconstructed phase maps were quantitatively evaluated to demonstrate its effectiveness for in situ experiments and low-dose experiments on beam-sensitive materials. [ABSTRACT FROM AUTHOR]

The performance of a direct electron detector using silicon-on-insulator (SOI) technology in a low-voltage transmission electron microscope (LVTEM) is evaluated. The modulation transfer function and detective quantum efficiency of the detector are measured under backside illumination. The SOI-type detector is demonstrated to have high sensitivity and high efficiency for the direct detection of low-energy electrons. The detector is thus considered suitable for low-dose imaging in an LVTEM. [ABSTRACT FROM AUTHOR]

A voltage‐applicable heating specimen holder is developed to observe solid oxide fuel cells (SOFCs) in an environmental transmission electron microscope. An SOFC specimen can be heated and has a voltage applied in an oxygen gas atmosphere using the holder. Oxygen ion migration and redox reactions in the specimen could also be realized. The heating unit, which consists of nickel–chromium alloy mounted on the tip of the developed specimen holder, can heat the specimen up to 1200 K in an oxygen gas atmosphere. A specimen preparation method for the SOFC structure is also established using a focused ion beam technique. The holder has high stability for high‐resolution imaging and electron energy loss spectroscopy under the in situ condition. The mechanical and electrical stabilities are estimated from high‐resolution images and electron energy loss spectra of the heated and voltage‐applied specimen in an oxygen gas atmosphere. The developed holder is a powerful tool to reveal the microstructural and electronic structural changes that occur by electrochemical reactions at the interfaces of an SOFC. [ABSTRACT FROM AUTHOR]

When two different materials come into contact, mobile carriers redistribute at the interface according to their potential difference. Such a charge redistribution is also expected at the interface between electrodes and solid electrolytes. The redistributed ions significantly affect the ion conduction through the interface. Thus, it is essential to determine the actual distribution of the ionic carriers and their potential to improve ion conduction. We succeeded in visualizing the ionic and potential profiles in the charge redistribution layer, or space‐charge layer (SCL), formed at the interface between a Cu electrode and Li‐conductive solid electrolyte using phase‐shifting electron holography and spatially resolved electron energy‐loss spectroscopy. These electron microscopy techniques clearly showed the Li‐ionic SCL, which dropped by 1.3 V within a distance of 10 nm from the interface. These techniques could contribute to the development of next‐generation electrochemical devices. Interest in the interface: Electron holography and spatially resolved electron energy‐loss spectroscopy were used to directly visualize electric potential and Li‐ion profiles in a Li‐ionic space‐charge layer (SCL) at the interface between an electrode and a solid electrolyte. The potential of the SCL dropped by 1.3 V within 10 nm from the interface. [ABSTRACT FROM AUTHOR]

Distribution of lattice strain in a GaAsP/GaAs superlattice with a periodicity of 10 nm thickness, deposited on a 100 nm GaAs basal layer has been measured by nano-beam electron diffraction. The superlattice on the (001) plane of the basal GaAs layer shows a constant lattice strain from the bottom to the top layers, whereas the superlattice on the basal GaAs surface sloped by 16° from the (001) plane shows a variation of the lattice strain and crystal orientation. The difference of the strain distributions was discussed from the viewpoint of average strain. This tilt was explained by an atomistic model. [ABSTRACT FROM AUTHOR]

Pulse-mode operation was realized in spin-polarized transmission electron microscopy (SP-TEM) using a laser-driven electron gun with a GaAs-GaAsP strained-layer-superlattice photocathode. TEM images were acquired with a pulsed electron beam with a 5-μs pulse duration. Phase locking of wobbling TEM images was demonstrated using a pulsed beam with a 1-kHz repetition frequency, which matched the image wobbling frequency. It was found that in composite images formed by superimposing 2 × 104 separate single-pulse exposures, the amount of image blurring due to wobbling was a linear function of the pulse duration. These results suggest the possibility of pump-probe measurements in SP-TEM using the pulsed electron beam as a probe, allowing nanometer-scale time-resolved spin mapping. [ABSTRACT FROM PUBLISHER]

A highly precise determination of lattice parameters using higher-order Laue zone (HOLZ) reflections observed in nano-beam electron diffraction is presented. The introduction of more than 40 HOLZ reflections, whose positions are corrected by considering the aberration of the electron optics and are determined with an accuracy of 0.04 nm−1, allows us to achieve a remarkable high precision of a 0.02% error, which is four times higher than the precision without HOLZ reflections. [ABSTRACT FROM PUBLISHER]

The present study experimentally examines how an electron vortex beam with orbital angular momentum (OAM) undergoes diffraction through a forked grating. The nth-order diffracted electron vortex beam after passing through a forked grating with a Burgers vector of 1 shows an OAM transfer of nħ. Hence, the diffraction patterns become mirror asymmetric owing to the size difference between the electron beams. Such a forked grating, when used in combination with a pinhole located at the diffraction plane, could act as an analyzer to measure the OAM of input electrons. [ABSTRACT FROM AUTHOR]

We report the production of electron vortex beams carrying large orbital angular momentum (OAM) using micro-fabricated spiral zone plates. A series of the spherical waves, focussing onto different positions along the propagating direction of the electron beam, were observed. The nth order vortex beam has an OAM n times larger than that of the first-order vortex beam. We observed an electron vortex with an OAM up to in a high-order diffracted wave. A linear dependence of the diameter of the vortex beam on the OAM was observed, being consistent to numerical simulations. [ABSTRACT FROM AUTHOR]

The electron intensity of a beam from an amorphous surface layer on a crystal transmission electron microscopy (TEM) specimen has been found to have sufficient coherence to produce fringes in interferograms, created by interfering two electron diffracted beams from the crystal, using a method of electron interference referred to as diffracted beam interferometry. This interference method involves amplitude splitting of the electron beam by means of a crystal with a thin amorphous layer on its surface. The amorphous intensity is transferred along with the crystal's Bragg diffracted beams and is then self-interfered when the crystal's Bragg diffracted beams are interfered by an electron biprism. The interference fringes in the interferograms exist in low to high electron scattering angles. The spatial frequency of the amorphous intensity fringes depends on the Bragg angle of the crystal's interfered diffracted beams. It is shown that the absolute phase of the amorphous intensity is possibly obtained using a Cs-corrected TEM and two interfering diffracted beams having equal but opposite phases. This method of interference is a good step towards measuring the phase of amorphous materials that is useful in determining their complex atomic structures. [ABSTRACT FROM AUTHOR]

Kikuchi patterns of an MgO crystal at the [110] incidence have been taken by a sub-angstrom electron beam focused on the single atom-column. A significant change in intensity has been observed in the 111 band; that is, the contrast in the central and side bands is reversed depending on the illuminated atom-column. The contrast reversal in the 111 band has been reproduced by multislice simulation using the frozen-phonon approach. The beam-position dependence of the 111 band intensity can be interpreted by electron channelling and the reciprocity theorem. The anomalous Kikuchi pattern can be a probe for identifying the illuminated atom-column, which is useful for column-by-column electron energy-loss spectroscopy and X-ray emission spectroscopy. [ABSTRACT FROM AUTHOR]

A method to determine lattice parameters and parameters characterizing the bending strain of the lattice, the direction and magnitude of the displacement field of the bending strain, by using higher-order Laue zone (HOLZ) reflection lines observed in convergent-beam electron diffraction patterns is proposed. In this method, all of the parameters are simultaneously determined by a fit of two Hough transforms of experimental and kinematically simulated HOLZ line patterns. This method has been used to obtain two-dimensional maps of lattice parameter a, the direction and relative magnitude of the displacement field in a Si substrate near a SiGe/Si interface. [ABSTRACT FROM AUTHOR]

For the first time, the electron intensity on the diffraction plane from amorphous transmission electron microscope (TEM) specimens has been found to have sufficient coherence to produce fringes in interferograms that were created using a wavefront splitting method of diffracted beam interferometry. The fringes were found to exist from low to high electron-scattering angles. Their spatial frequency depended on the angular overlap of the interfering beams, which was controlled by an electron biprism. From these interferograms, phase information of amorphous materials, which is information now lacking and required for determining their atomic structures, was obtained. An immediate application of this interference is a new method to determine the spatial resolution of the TEM that occurs at the shear angle for fringe disappearance. [ABSTRACT FROM AUTHOR]

A structural change of an Al72Ni20Co8decagonal quasicrystal into the S1-type superlattice ordered phase has been observed at about 400°C by in-situ high-resolution electron microscopy. It is considered that the formation of the S1-type superlattice order is attributed to the structural change of the atom cluster with 2 nm diameter from mirror symmetric one to fivefold symmetric one and the disappearance of 1.2-nm intercluster bonds. [ABSTRACT FROM AUTHOR]

Electron channeling patterns, which display the intensity variation of characteristic X-ray emission as a function of incident beam orientation, have been taken from an S1-type superlattice-ordered decagonal quasicrystal of Al70Ni18Co12, which shows diffuse streaks on and halfway between Bragg spot layers perpendicular to the decagonal direction in the electron diffraction patterns. The channeling patterns show that Al atoms and transition metals occupy different sublattice sites, and that both Ni and Co atoms randomly occupy the same sublattice sites, that is, they are disordered. This indicates that the origin of the diffuse streaks is not related to a chemical order between Ni and Co, but is caused only by a topological order, such as a small displacement of atoms. [Copyright &y& Elsevier]

Structural variations in local areas such as the star-shaped and butterfly-shaped tiles of a noncentrosymmetric decagonal quasicrystal of Al70Ni15Fe15 have been investigated by using the high-angle annular dark-field scanning transmission electron microscope method. It has been demonstrated that the variations of the star-shaped and butterfly-shaped tiles in Al70Ni15Fe15 are uniquely decomposed into the 1-nm column-pairs [Saitoh et al., J. Phys. Soc. Jpn. 68 (1999) 2886], which is the basic structural unit of the τ2-inflated Al13Co4 approximant. [Copyright &y& Elsevier]

Si nanocrystals grown on cubic SiC have been characterized using high‐resolution transmission electron microscopy. At lower temperatures nanocrystals grow in two different orientations, whereas at higher temperatures they grow in a single preferred orientation. The nanocrystals are shown to be unstrained; in some cases possibly due to the presence of a thin amorphous wetting layer. [ABSTRACT FROM PUBLISHER]

Discusses the distinction of space groups (I23 and I2[sub 1]3) and (I222 and I2[sub 1]2[sub 1]2[sub 1]) using coherent convergent-beam electron diffraction. Identification of the handedness of space groups; Results of kinematical structure-factor calculations.

Background: We have developed a system to monitor, simultaneously and continuously, ambulatory SaO2 measured using a pulse-oximeter and ECG data for 24 hours. Methods: The ambulatory SaO2-ECG monitoring system consisted of a portable monitoring device (SM50) with two channels for ECG data and one channel for SaO2 data input; a sensor for SaO2 recording; and a pulse-oximeter. An ambulatory monitoring analyzer was used. The SaO2 report from the present analyzer included two types of data (i.e., a profile of heart rate [HR], pulse rate [PR], and SaO2 value per min), and a trend graph of HR, arrhythmia, ST level and slope, PR, and SaO2 per minute. We also designed and produced an analytical program to automatically remove noise errors relating to the SaO2 measurement. Results: Using this system, we performed a clinical study on ten healthy volunteers (Group N) and seven patients with chronic pulmonary diseases (Group CPD) to evaluate the usefulness of the system as a diagnostic means for respiratory failure and arrhythmia. Group N showed a stable value of 90% or over in SaO2 during the 24-hour monitoring while Group CPD showed values under 90% SaO2 in all patients at rest during the night or after a 15-minute walk. Transient atrial tachycardia (TAT) was observed in 3 of 7 CPD patients, and each episode was preceded by a decrease of SaO2. The occurrence of a single or double ventricular extrasystole was high in Group CPD compared with Group N (1.21 ± 0.89 vs 0.6%± 0.3%, P < 0.05), its occurrence was not associated with a decrease in SaO2. Conclusions: In outpatients, especially patients who are taken care of at home, the present system will certainly contribute greatly to the diagnosis of respiratory failure and arrhythmia as well as to evaluate the effects on these diseases of therapy. In addition it is suggested that in CPD, patients'hypoxemia may induce TAT. [ABSTRACT FROM AUTHOR]

The symmetry of the p-hole state of a superconductor of MgB2 was studied by the observation of inelastic scattering anisotropy of fast electrons accompanied by boron K-shell excitation. A series of the energy-selected diffraction patterns taken at successive energy losses were decomposed into two components; the σ and π components, respectively. The magnitudes of the σ and π components as a function of energy loss, or partial electron energy-loss spectroscopy spectra, show a good correspondence to the partial density of states obtained by a theoretical calculation. A significant occupation of the σ state at just above the Fermi level, which is considered to play an important role for the formation of the superconductive state, was confirmed. [ABSTRACT FROM AUTHOR]

We first tried to determine the thickness of both Si-on-Mo and Mo-on-Si interdiffusion layers inherent in the Mo/Si multilayer films by taking high angle angular dark-field-scanning transmission electron microscopy (HAADF-STEM) images. Secondly, the origin of 2–5% shortage of the measured extreme ultraviolet (EUV) reflectivity relative to that expected from the Fresnel equation has been investigated from two possible viewpoints: one, the presence of residual Xe gas atoms incorporated into the film during deposition in the reduced Xe gas atmosphere, and the other, a gradual shift of the layer periodicity over an entire cycle of repeated depositions. By analyzing the grazing incident X-ray reflectivity (GIXR) spectra for the 50-layer films, we were able to demonstrate that the latter is responsible for lowering the EUV reflectivity. [ABSTRACT FROM AUTHOR]

An experimental method to measure the strain through the thickness of a crystal is demonstrated. This enables the full three-dimensional stress–strain state of a crystal at the nanoscale to be determined taking the current practice from two-dimensional strain state determination. Knowing the 3D strain state is desired by crystal growers in order to improve their crystal's quality. This method involves combining electron diffraction with electron interferometry in a transmission electron microscope. The electron diffraction uses a split higher order Laue zone (HOLZ) line and the electron interferometry uses an electron biprism. [ABSTRACT FROM AUTHOR]

High-temperature phase transition of lanthanum niobium titanate La0.64(Ti0.92,Nb0.08)O3 has been studied using neutron powder diffraction and the Rietveld method. The material is orthorhombic (Cmmm) between 295 and 534 K, while it is tetragonal (P4/mmm) between 637 and 740 K. The anti-phase tilt along the b axis of the oxygen octahedron around Ti and Nb atoms was found to induce the tetragonal-to-orthorhombic phase transition. The angle of the tilt and the b/a ratio of cell parameters decrease with an increase of temperature and become 0° and unity, respectively, at a transition temperature between 534 and 637 K. [Copyright &y& Elsevier]