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REBaCuO (RE: rare earth) bulk superconductors, whose microstructures can be controlled by quench and melt growth (QMG) processing, have a high critical current density Jc, which makes them well suited for use in practical applications. Through a combination of electron holography and a focused ion-beam technique, we succeeded in visualizing a fluxon pinned by an insulating particle in a QMG bulk Y-Ba-Cu-O superconductor. We also clarified the magnetic flux distribution in the vicinity of the insulating particles at different temperatures in a uniform external magnetic field. [ABSTRACT FROM AUTHOR]

Triple-biprism electron interferometry has been developed to flexibly control all interference parameters, i.e., interference region (size and shape), fringe spacing, and fringe angle. Each filament electrode of the upper and middle electron biprisms is installed in the individual image planes of the objective and first magnifying lenses, respectively. One more filament electrode of the lower biprism is set between the crossover plane and image plane behind the second magnifying lens. The azimuth angle between the upper and middle filaments is set at 90°, and lower filament is set at about 45° for both of the above filaments. Among many possible optical setups, we chose the setup with the easiest and most flexible control of all the interference parameters through theoretical investigation and experimental confirmation. The interferometer was constructed in a 1×106 V field emission electron microscope, and the overall performance was demonstrated and investigated experimentally. [ABSTRACT FROM AUTHOR]

High-resolution electron holography has been achieved by using a double-biprism interferometer implemented on a 1 MV field emission electron microscope. The interferometer was installed behind the first magnifying lens to narrow carrier fringes and thus enabled complete separation of sideband Fourier spectrum from center band in reconstruction process. Holograms of Au fine particles and single-crystalline thin films with the finest fringe spacing of 4.2 pm were recorded and reconstructed. The overall holography system including the reconstruction process performed well for holograms in which carrier fringes had a spacing of around 10 pm. High-resolution lattice images of the amplitude and phase were clearly reconstructed without mixing of the center band and sideband information. Additionally, entire holograms were recorded without Fresnel fringes normally generated by the filament electrode of the biprism, and the holograms were thus reconstructed without the artifacts caused by Fresnel fringes. [ABSTRACT FROM AUTHOR]

Presents a study which described a phase-shifting interferometry using a generalized algorithm for measuring the electron phase in a transmission electron microscope. Discussion of the generalized phase-shifting algorithm; Measurement of initial phase; Experimental results.

Focuses on a study which described a method of reconstructing three-dimensional magnetic fields using electron-holographic interferometry. Analysis of a measured two-dimensional phase distributions to reveal the projected magnetic flux structure of a microscopic object; Development of an algorithm for reconstructing the magnetic flux density in three dimension from the phase distributions at different viewing directions; Presentation of an application to a barium particle.

Examines the sensitivity-enhanced electron holography and its application to magnetic recording investigations. Information on the quantitative measurement of magnetic flux; Distribution of a leakage magnetic field; Calculation of the magnetic field vector component.

Introduces a developed application of electron holography to magnetic domain structure observation. Background on electron holography; Information on electromagnetism; Methods used in the formation of the electron holography.

Skyrmions are nanoscale spin textures that are viewed as promising candidates as information carriers in future spintronic devices. Skyrmions have been observed using neutron scattering and microscopy techniques. Real-space imaging using electrons is a straightforward way to interpret spin configurations by detecting the phase shifts due to electromagnetic fields. Here, we report the first observation by electron holography of the magnetic flux and the three-dimensional spin configuration of a skyrmion lattice in Fe0.5Co0.5Si thin samples. The magnetic flux inside and outside a skyrmion was directly visualized and the handedness of the magnetic flux flow was found to be dependent on the direction of the applied magnetic field. The electron phase shifts φ in the helical and skyrmion phases were determined using samples with a stepped thickness t (from 55 nm to 510 nm), revealing a linear relationship (φ = 0.00173t). The phase measurements were used to estimate the three-dimensional structures of both the helical and skyrmion phases, demonstrating that electron holography is a useful tool for studying complex magnetic structures and for three-dimensional, real-space mapping of magnetic fields. [ABSTRACT FROM AUTHOR]

The three-dimensional spin structure of the magnetic vortex of FeSiB, an amorphous soft magnetic material, was investigated by holography observation and computer simulation. Magnetization distribution in the neighborhood of the vortex center was estimated from the phase distribution obtained by holography observation. To confirm this magnetization distribution, sample-tilting experiments were performed: when the sample was tilted with respect to the electron beam direction, the phase-image center was found to shift along the tilting axis. Finite-element computer simulation was carried out to estimate the amount of shifts of the phase-image center in the sample tilting from the experimental magnetization distributions in the no sample-tilting conditions. We found that the simulated shifts of the phase-image center were in good agreement with those in the sample-tilting experiment, thus confirming the magnetization distribution near the vortex center obtained by holography observation. [ABSTRACT FROM PUBLISHER]

Three-dimensional (3D) reconstruction experiments were carried out by observing high-resolution 3D electrostatic potential distributions of Pt nanoparticles using off-axis electron holographic tomography. These Pt nanoparticles were mounted on the surfaces of amorphous silicon pillars. In order to realize high-resolution observation, we developed a mechanically stable 3D specimen holder with small specimen drifts and vibrations. From the 3D electrostatic potential distribution data of Pt nanoparticles (2.0 nm in diameter), we obtained the resolution of 1.5 nm. [ABSTRACT FROM PUBLISHER]

The magnetic interaction between the pole tip of a single-pole head and a pseudo soft underlayer in perpendicular magnetic recording was observed by electron holography. The magnetic flux density inside the soft underlayer was quantitatively evaluated. The distribution of magnetic flux density was calculated using the finite element method, and the influences of the modulation of the reference wave and stray fields were investigated by comparison with experimental results. The flux density observed was found to be underestimated due to the modulation of the phase shift in reference wave. The magnetic flux measured experimentally was larger than that inside the specimen because of the relatively large stray fields above and below the specimen in the direction of the electron beam. [ABSTRACT FROM AUTHOR]

The article discusses the Aharonov-Bohm (AB) effect, a modern cornerstone of quantum mechanics which was scrutinized and spawned experimental test. It talks about the property of AB effect which cites the effect of stray fields emanating from a solenoid. Furthermore it highlights the interference between quantum mechanical amplitudes for alternative paths of single particle.

Quantum phenomena have become directly observable with the development of advanced techniques such as coherent field-emission electron beams, sensitive detectors, and microlithography. Examples are the single-electron build-up of an interference pattern, which contains, as R. Feynman describes in his textbook, the heart of quantum mechanics, and the Aharonov–Bohm (AB) effect, which indicates the physical significance of gauge fields. Using the AB effect, i.e., the fundamental principle behind the interaction of an electron wave with electromagnetic fields, new ways to directly observe previously unobservable microscopic quantum objects and phenomena were developed by detecting the phase of electrons. [ABSTRACT FROM AUTHOR]

Fundamental aspects of quantum mechanics, which were discussed only theoretically as "thought experiments" in the 1920s and 1930s, have begun to frequently show up in nanoscopic regions owing to recent rapid progress in advanced technologies. Quantum phenomena were once regarded as the ultimate factors limiting further miniaturization trends of microstructured electronic devices, but now they have begun to be actively used as the principles for new devices such as quantum computers. To directly observe what had been unobservable quantum phenomena, we have tried to develop bright and monochromatic electron beams for the last 35 years. Every time the brightness of an electron beam improved, fundamental experiments in quantum mechanics became possible, and quantum phenomena became observable by using the wave nature of electrons. [ABSTRACT FROM AUTHOR]

A newly developed 1 MV field‐emission transmission electron microscope has recently been applied to the field of superconductivity by utilizing its bright and monochromatic field‐emission electron beam. This microscope allows individual magnetic vortices inside high‐Tc superconductors to be observed, thus, opening the way to investigate the unusual behaviour of vortices, which reflects the anisotropic layered structure of these superconducting materials. One example is the observation of the arrangements of chain vortex lines that are formed when a magnetic field is applied obliquely to the layer plane of the materials. [ABSTRACT FROM PUBLISHER]

A bright field‐emission electron beam was used to observe magnetic vortices in superconducting thin films by electron holography and Lorentz microscopy. Especially in Lorentz microscopy, the dynamic behaviour of individual vortices became directly observable for the first time. As material defects can be observed simultaneously, the vortex pinning phenomena, which are indispensable for practical applications of superconductors, can now be observed microscopically and dynamically. This study revealed the existence of various kinds of vortex movements, such as individual hopping among defects, vortex rivers, and vortex–antivortex pair annihilation. [ABSTRACT FROM PUBLISHER]

We developed a 1 MV field-emission transmission electron microscope. This paper reports details and specifications of the instrument. The microscope was designed to obtain a bright and coherent electron beam by using the field emission gun equipped with a pre-accelerating magnetic lens and the highvoltage power supply with high stability (0.5 ppm min−1). Using this microscope, the brightness of 1.8×1010 A cm−2 sr−1 and the lattice resolution of 49.8 pm were attained. [ABSTRACT FROM PUBLISHER]

Electron interference has been investigated at an industrial laboratory of Hitachi, Ltd. for the past 30 years thanks to the encouragement and support of C. N. Yang, who retired from the State University of New York in 1999. This paper reports here fundamentals and applications of electron interference experiments we have carried out including our relation to C. N. Yang, and is based on a talk made in honor of him at the "Symmetries and Reflections" Symposium held at Stony Brook in May 1999. [ABSTRACT FROM AUTHOR]

Unstained ferritin molecules were observed as a contour map of the phase of the transmitted electron wave for the first time, by means of phase-difference amplified holographic interference electron microscopy. In addition to the outer shapes of the ferritin cores, the surrounding protein layers 6 nm in thickness could also be recognized in these contour maps. [ABSTRACT FROM PUBLISHER]

The new technique of electron holography which has recently been put to practical use with a field-emission electron microscope is reviewed. Electron holography enables discernment of the electron phase, an aspect which has not been fully utilized so far in electron microscopy. Among several applications of electron holography, interference microscopy in particular was proven to be promising for practical purposes, since the contour fringes of the transmitted electron wavefront indicated the thickness contours of a homogeneous specimen and the magnetic lines of force of a ferromagnetic specimen. Further developments of electron holography technique are expected to open new possibilities of both observation and measurements in atomic dimensions. [ABSTRACT FROM PUBLISHER]

The magnetic flux distribution for fine iron particles less than 200 nm in size with the habit of rhombic dodecahedron is studied by high voltage electron microscopy and electron holography. It is concluded that a particle has a magnetic flux component rotated in a {110} plane and enclosed within it. The advantage of using high voltage electron microscopy for examining the magnetic structure is also discussed. [ABSTRACT FROM PUBLISHER]

A field emission electron microscope with highly stabilized gun and illuminating system was developed. Several experiments were made to demonstrate the high performance of the microscope. The brightness of the beam was more than that of the conventional ones, which feature was demonstrated by taking 300 Fresnel fringes and 3,000 bi-prism fringes. Furthermore, monochromatic feature of the microscope makes the effect of chromatic aberration smaller and the half-spacing fringes of nickel {220} planes (1/2 d=62Å) were observed. [ABSTRACT FROM PUBLISHER]

The development of a coherent field-emission electron beam has made it possible to observe microscopic magnetic lines of force by detecting the electron-wave phase shifts that are due to vector potentials. Electron-holographic interference microscopy has been used to observe magnetic lines of force of magnetic vortices in superconductors, and Lorentz microscopy has been used to observe the dynamics of the vortices. The observation of vortices not only helps us understand the microscopic mechanism of flux pinning, which holds the key to practical applications of superconductors, but also clarifies fundamental phenomena of superconductivity which have implications for more general physical phenomena. [ABSTRACT FROM AUTHOR]

Examines the multiplication factor of silicon (Si) avalanche photodiodes (APD) for the detection of monoenergetic electrons. Variables causing saturation in the multiplication mechanism of the Si APD; Impact of the space charge effect on a device with a larger breakdown voltage; Importance of the initial carrier concentration on the design of the APD.

Familial adenomatous polyposis (FAP), which includes familial polyposis coli (FPC) and the Gardner syndrome (GS), is a genetically determined premalignant disease of the colon inherited by a locus (APC) mapping within 5q15-q22. To elucidate the role of 5q loss in FAP tumorigenesis, we analysed 51 colorectal tumors and seven desmoids from 19 cases of FPC and five GS patients, as well as 15 sporadic colon cancers. RFLP analysis revealed a high incidence of allelic deletion in hereditary colon cancers as well as in sporadic colon cancers with a peak at the APC locus. APC loss resulted primarily from interstitial deletion or mitotic recombination. Combined tumor and pedigree analysis in a GS family revealed loss of normal 5q alleles in three tumors, including a desmoid tumor, which suggests the involvement of hemizygosity or homozygosity of the defective APC gene in colon carcinogenesis and, possibly, in extracolonic neoplasms associated with FAP. [ABSTRACT FROM AUTHOR]

We investigated possible association of and linkage between HLA and familial polyposis coli (FPC). In 182 individuals from 66 pedigrees of FPC and 108 individuals from a normal population, HLA-A,-B, and-C antigens were determined. When the frequencies of HLA antigens in 66 unrelated patients and in normal controls were compared, no association of FPC with HLA was observed. For the linkage analysis, HLA haplotypes of 17 affected sib pairs were investigated by the affected sib pair method. The number of pairs which shared two, one, and no haplotypes identical by descent was not significantly different from the number expected with random occurrence ( P>0.95). Finally, seven families were analyzed using Morton's sequential test. A maximum lod score of-0.056 at a recombination fraction of 0.4, and a lod of-3.089 at a recombination fraction of 0.05 were obtained. Therefore, there is neither an association of nor linkage between FPC and HLA. [ABSTRACT FROM AUTHOR]

Paternal age distribution for 1279 cases of Down's syndrome born in 1952-1968 was compared with the corresponding distribution for the general population, corrected for the maternal age as well as for the year of birth of the patients. Although there was no difference in the mean paternal age, the two distributions differed significantly, largely due to the excess of fathers aged 55 years and over and to the deficit of those aged 40-44 years in the patients born to mothers aged 30 years and over. The overall pattern of the relative incidence of Down's syndrome with advancing paternal age, with maternal age controlled, seems consistent with the hypothesis proposed by Stene et al. (1977). It increased from 0.8 for fathers aged 20-24 years slowly up to 1.2 for those aged 45-49 years, though with an intermediate drop to 0.8 at the age of 40-44 years, and then sharply to 2.4 for those aged 55 years and over. This rising pattern of the relative incidence with paternal age was essentially the same for the patients born in 1952-1960 and for those born in 1961-1968, although the slope was less steep in the latter than in the former group. [ABSTRACT FROM AUTHOR]