1,318 research outputs found
Electron emission from conduction band of diamond with negative electron affinity
Experimental evidence explaining the extremely low-threshold electron
emission from diamond reported in 1996 has been obtained for the first time.
Direct observation using combined ultraviolet photoelectron spectroscopy/field
emission spectroscopy (UPS/FES) proved that the origin of field-induced
electron emission from heavily nitrogen (N)-doped chemical vapour deposited
(CVD) diamond was at conduction band minimum (CBM) utilising negative electron
affinity (NEA). The significance of the result is that not only does it prove
the utilisation of NEA as the dominant factor for the extremely low-threshold
electron emission from heavily N-doped CVD diamond, but also strongly implies
that such low-threshold emission is possible from other types of diamond, and
even other materials having NEA surface. The low-threshold voltage, along with
the stable intensity and remarkably narrow energy width, suggests that this
type of electron emission can be applied to develop a next generation vacuum
nano-electronic devices with long lifetime and high energy resolution.Comment: 17 pages, 4 figures, Phys. Rev. B in pres
Multi-Triplet Magnons in SrCu(BO) Studied by Thermal Conductivity Measurements in Magnetic Fields
We have measured the thermal conductivity parallel to the a-axis of the
Zn-free and 1% Zn-substituted SrCuZn(BO) in magnetic fields
up to 14 T, in order to examine the thermal conductivity due to the
multi-triplet magnons. It has been found that the thermal conductivity peak
observed in the spin gap state is suppressed by the substitution of Zn for Cu
in high magnetic fields above 6 T, while it is not changed in low magnetic
fields below 6 T. The results suggest that the thermal conductivity peak in the
spin-gap state of SrCu(BO) is composed of not only thermal
conductivity due to phonons but also that due to the multi-triplet magnons in
high fields above 6 T.Comment: 7 pages, 2 figure
Angular Momentum of Fission Products in 232Th+p System (II)
開始ページ、終了ページ: 冊子体のページ付
Enhancement of the Thermal Conductivity in gapped Quantum Spin Chains
We study mechanism of magnetic energy transport, motivated by recent
measurements of the thermal conductivity in low dimensional quantum magnets. We
point out a possible mechanism of enhancement of the thermal conductivity in
gapped magnetic system, where the magnetic energy transport plays a crucial
role. This mechanism gives an interpretation for the recent experiment of
CuGeO_3, where the thermal conductivity depends on the crystal direction.Comment: 4 pages, 2 figure
Thermomagnetic Power and Figure of Merit for Spin-1/2 Heisenberg Chain
Transport properties in the presence of magnetic fields are numerically
studied for the spin-1/2 Heisenberg XXZ chain. The breakdown of the
spin-reversal symmetry due to the magnetic field induces the magnetothermal
effect. In analogy with the thermoelectric effect in electron systems, the
thermomagnetic power (magnetic Seebeck coefficient) is provided, and is
numerically evaluated by the exact diagonalization for wide ranges of
temperatures and various magnetic fields. For the antiferromagnetic regime, we
find the magnetic Seebeck coefficient changes sign at certain temperatures,
which is interpreted as an effect of strong correlations. We also compute the
thermomagnetic figure of merit determining the efficiency of the thermomagnetic
devices for cooling or power generation.Comment: 8 page
Successful Late Management of Esophageal Perforation with T-Tube Drainage
The late management of spontaneous esophageal perforation is the most challenging problem for the surgeon. In this paper, we present a case in whom a spontaneous esophageal perforation was successfully treated by T-tube drainage after unsuccessful conservative treatment. The patient, a 68-year-old male, was admitted to the hospital with sudden upper abdominal pain. After 2 days, esophageal perforation was diagnosed, and conservative management was begun. Thereafter, the subcutaneous emphysema disappeared, and the patient's temperature decreased. However, on day 13, the patient's temperature spiked above 38°C, and computed tomography showed a mediastinal abscess. An emergency left thoracotomy with laparotomy was performed. Since a 2-cm longitudinal perforation with severe inflammatory reactions was observed, the T-tube drainage method was performed. The patient was discharged without postoperative complications and has not experienced any gastrointestinal symptoms, such as gastroesophageal reflux or dysphagia. In conclusion, the T-tube drainage method appears to be a simple and effective method for the late management of esophageal perforation with severe inflammatory reaction
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