Dynamic Observation of Vortices in Superconductors Using Electron Waves

1995 ◽  
Vol 404 ◽  
Author(s):  
A. Tonomura
Keyword(s):  
Electron Beam ◽  
Field Emission ◽  
Direct Observation ◽  
Point Defects ◽  
Lorentz Microscopy ◽  
Dynamic Observation ◽  
Emission Electron ◽  
Coherent Field ◽  
Lines Of Force

AbstractIndividual vortices in superconductors were directly and even dynamically observed by using a “coherent” field emission electron beam. Magnetic lines of force of vortices were quantitatively observed in a holographic interference micrograph and their dynamics were observed by Lorentz microscopy. The interaction of vortices with both line- and point-defects was investigated by direct observation.

Electron holography for magnetic property study of materials

1990 ◽  
Vol 48 (4) ◽  
pp. 392-393
Author(s):  
Akira Tonomura
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Phase Distribution ◽  
Magnetic Domain ◽  
Interference Microscopy ◽  
Electron Holography ◽  
Lorentz Microscopy ◽  
Coherent Field ◽  
Electron Interference ◽  
Intuitive Interpretation

An electron beam is often modulated, only in phase and not in intensity. When the beam passes through a magnetic field or a ferromagnetic thin film which can be regarded as pure phase objects. Therefore, great defocusing is indispensable for magnetic domain observation in Lorentz microscopy. Electron interference microscopy, however, can directly display the phase distribution of an electron beam in an in-focus electron micrograph, and consequently should provide direct information about magnetic fields.The development of a coherent field emission electron beam has opened a way to such a possibility using electron holography in which the phase-amplified phase distribution can be displayed as an interference micrograph. In addition, contour fringes have been interpreted as in-plane magnetic lines of force. Such an intuitive interpretation is possible for the following reason (Fig.1). An incident wavefront is displaced by the vector potential circulating around a magnetic field.

Development of a 1-MV Field-Emission Electron Microscope III. Electron Optical Design and Development of Field-Emission Electron Gun

2000 ◽  
Vol 6 (S2) ◽  
pp. 1142-1143
Author(s):  
Takaho Yoshida ◽  
Takeshi Kawasaki ◽  
Junji Endo ◽  
Tadao Furutsu ◽  
Isao Matsui ◽  
...  
Keyword(s):  
Electron Beam ◽  
Field Emission ◽  
Optical Design ◽  
Electron Gun ◽  
Electron Holography ◽  
Optimized Design ◽  
Emission Electron ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Aharonov Bohm

Bright and coherent electron beams have been opening new frontiers in science and technology. So far, we have developed several field-emission transmission electron microscopes (FE-TEM) with increasing accelerating voltages to provide higher beam brightness. By using a 200-kV FE-TEM and electron holography techniques, we directly confirmed the Aharonov-Bohm effect. A 350-kV FE-TEM equipped with a low-temperature specimen stage enabled us to observe moving vortices in superconductors.2 Most Recently, we have developed a new 1-MV FE-TEM with a newly designed FE gun to obtain an even brighter and more coherent electron beam.Electron beam brightness, Br, defined in Figure 1, is suitable for measuring the performance of electron guns, since both lens aberrations and mechanical/electrical vibrations contribute to a decrease in beam brightness, and beam coherency is proportional to (Br)1/2. Therefore, we optimized design of the illuminating system and its operation by maximizing the electron beam brightness.

Evaluation of a 100 kV thermal field emission electron-beam nanolithography system

2000 ◽  
Vol 18 (6) ◽  
pp. 3089 ◽  
Author(s):  
D. M. Tennant ◽  
R. Fullowan ◽  
H. Takemura ◽  
M. Isobe ◽  
Y. Nakagawa
Keyword(s):  
Electron Beam ◽  
Field Emission ◽  
Thermal Field ◽  
Emission Electron

Fabrication and beam characteristics of an ultra-sharp electrode for field emission electron beam

2004 ◽  
Author(s):  
Seong-Soo Kim ◽  
Jong-Hang Lee ◽  
Youn-Chan Yim ◽  
Jung-Woo Hyun ◽  
Cheol-Woo Park ◽  
...  
Keyword(s):  
Electron Beam ◽  
Field Emission ◽  
Emission Electron ◽  
Beam Characteristics

Holographic contrast transfer theory

1992 ◽  
Vol 50 (2) ◽  
pp. 984-985
Author(s):  
R. Plass ◽  
L. D. Marks
Keyword(s):  
Electron Beam ◽  
Transfer Function ◽  
Field Emission ◽  
Electron Holography ◽  
Contrast Transfer Function ◽  
Beam Focusing ◽  
Emission Electron ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Image Position

With the advent of reliable cold field emission transmission electron microscopes there is substantial interest in using the amplitude and phase information recorded in electron holograms to optically or numerically correct for the coherent aberrations of transmission electron microscopes. However electron holography cannot compensate for incoherent aberrations. The derivation of the contrast transfer function for off axis electron holography in this paper shows there is no fundamental improvement in resolution for electron holography over conventional transmission electron microscopy.Evaluating the contrast transfer function involves mathematically following an electron beam through a field emission electron microscope set up for off axis electron holography. Due to the high coherence of the field emission electron beam coherent aberrations caused by the pre-specimen beam focusing system must be accounted for. Starting with a spacial frequency distribution, C(v), for the electron beam leaving the gun, the electron beam is limited by the condenser aperture and coherently aberrated by the condenser lens and objective pre-field as it passes to the specimen region:

Applications of electron holography to ferromagnetic and superconductive materials

1994 ◽  
Vol 52 ◽  
pp. 546-547
Author(s):  
Akira. Tonomura
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Phase Distribution ◽  
Phase Measurement ◽  
Image Point ◽  
Electron Holography ◽  
Transmission Electron ◽  
Coherent Field ◽  
Electron Lens ◽  
Lines Of Force

Electromagnetic fields are not observable with conventional electron microscopy: The fields deflect an incident electron beam but no contrast is produced in the electron micrograph for the fields since all the electrons deflected at an object point are focused into a single image point through the electron lens. The information about the electomagnetic fields is included in the deflection distribution or the phase distribution of an electron beam, which is lost in electron micrographs. Electron interferometry has been carried out since 1950s using a transmission electron microscope equipped with an electron biprism to make ultra-fine measurements. The advent of a "coherent" field-emission electron beam has greatly expanded the range of applications and possibilities: Electric and magnetic fields are directly observed as equipotential lines and magnetic lines of force in an electron-holographic interference micrograph. Precision in phase measurement has increased to 2π/50 thanks to a phase amplification technique peculiar to holography.In magnetic field observation, contour fringes in an interference micrograph directly indicate projected magnetic lines of force in h/e flux units. An example of a magnetic field micrograph is shown in Fig. 1.

YBCO SQUIDs fabricated by field-emission electron beam source

1999 ◽  
Vol 9 (2) ◽  
pp. 3089-3092
Author(s):  
S.-J. Kim ◽  
J. Chen ◽  
Y. Mizugaki ◽  
K. Nakajima ◽  
T. Yamashita
Keyword(s):  
Electron Beam ◽  
Field Emission ◽  
Beam Source ◽  
Emission Electron

Silicon field emission electron beam sources

1995 ◽  
Author(s):  
D. Palmer ◽  
J. Shaw ◽  
H. Gray ◽  
J. Mancusi ◽  
G.E. McGuire ◽  
...  
Keyword(s):  
Electron Beam ◽  
Field Emission ◽  
Emission Electron
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