Carrier dynamics and magneto-transport in Kondo-Hubbard model

The motion of a single hole in the antiferromagnetic ground state and in the paramagnetic state at high temperatures is studied in the Kondo-Hubbard model with Hund coupling. It is shown that the Hund coupling strongly reduces both band-width of the coherent state at the ground state and the mobility at high temperatures. Implications of the results to magneto-transport phenomena in manganites are presented.     

Carrier dynamics and magneto-transport in Kondo-Hubbard model

The motion of a single hole in the antiferromagnetic ground state and in the paramagnetic state at high temperatures is studied in the Kondo-Hubbard model with Hund coupling. It is shown that the Hund coupling strongly reduces both band-width of the coherent state at the ground state and the mobility at high temperatures. Implications of the results to magneto-transport phenomena in manganites are presented.     

Synchrotron radiation-stimulated photochemical reaction and its application to semiconductor processes

Recent results are reviewed on synchrotron radiation (SR)-excited photochemical reaction studies aimed at applications to semiconductor processes. Valence or core electronic excitations induced by SR irradiation and ensuing chemical reactions are classified and characterized by rate equations. Unique material selectivity in etching has been found. SiO₂ has been found to evaporate by SR irradiation and this phenomenon can be applied to the low-temperature surface cleaning of silicon. In the epitaxial growth of Silicon by ultrahighvacuum chemical vapor deposition using Si₂H₆, SR irradiation significantly lowers growth temperature beyond the low-temperature limit of thermal reaction. Lowering of the operating temperature by SR irradiation is especially effective in applications to the atomic layer epitaxial growth of silicon. The layer-by-layer process has been successfully demonstrated, confirming self-limiting adsorption of SiH₂Cl₂ and ensuring surface reactivation by SR irradiation.     

Electroorganic chemistry—XV : Electroreduction of sulfonium and ammonium salts. Formation of sulfonium ylids

In the electroreduction of sulfonium and ammonium salts, sulfonium ylid was generated from the sulfonium salt, whereas in the case of the ammonium salt, nitrogen ylid was not formed but the N+C bond was reductively cleaved. On the basis of the controlled potential electrolysis, it seems acceptable that the mechanism of formation of sulfonium ylid involves the direct electron transfer to the sulfonium salt as the initiation step.     

Correlation between interfacial structure and c-axis-orientation of LiNbO3 films grown on Si and SiO2 by electron cyclotron resonance plasma sputtering

Thin films of crystalline lithium niobate (LN) grown on Si(1 0 0) and SiO₂ substrates by electron cyclotron resonance plasma sputtering exhibit distinct interfacial structures that strongly affect the orientation of respective films. Growth at 460–600 °C on the Si(1 0 0) surface produced columnar domains of LiNbO₃ with well-oriented c-axes, i.e., normal to the surface. When the SiO₂ substrate was similarly exposed to plasma at temperatures above 500 °C, however, increased diffusion of Li and Nb atoms into the SiO₂ film was seen and this led to an LN–SiO₂ alloy interface in which crystal-axis orientations were randomized. This problem was solved by solid-phase crystallization of the deposited film of amorphous LN; the degree of c-axis orientation was then immune to the choice of substrate material.     

Improved liquid chromatographic separation of different proteins by designing functional surfaces of cattle bone-originated apatite

Spherical particles of cattle bone-originated hydroxyapatite (r-HAp) were prepared by dissolution-precipitation, spray-drying using a two fluid-nozzle apparatus, and subsequent heat treatment. The product had effective pore structures for liquid chromatographic separation of albumin, myoglobin, ribonuclease, lysozyme and cytochrome c. The activated surfaces of the r-HAp particles were easily prepared with desired proportions of P- and C-sites and appropriate acid-basic strength for selective protein adsorption by optimizing the synthesis conditions. Liquid chromatography columns packed with the particles exhibited high resolution and durability in protein separation, reflecting stable distribution of pore size.     

Photoresponsive rolling and bending of thin crystals of chiral diarylethenes

Dithienylhexafluorocyclopentene with (R)- or (S)-N-phenylethylamide substituents formed rod-like and 0.2-1.0 microm-thick platelike crystals by sublimation; upon UV irradiation, the crystals bent concavely to the incident light and finally rolled crystals were obtained; the bent crystals were reconverted to flat crystals by visible light irradiation.