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141.
Lavrov AN Kang HJ Kurita Y Suzuki T Komiya S Lynn JW Lee SH Dai P Ando Y 《Physical review letters》2004,92(22):227003
We use transport and neutron-scattering measurements to show that a magnetic-field-induced transition from noncollinear to collinear spin arrangement in adjacent CuO2 planes of lightly electron-doped Pr(1.3-x)La(0.7)CexCuO4 (x=0.01) crystals affects significantly both the in-plane and out-of-plane resistivity. In the high-field collinear state, the magnetoresistance (MR) does not saturate but exhibits an intriguing fourfold-symmetric angular dependence, oscillating from being positive at B//[100] to being negative at B//[110]. The observed MR of more than 30% at low temperatures induced by a modest modification of the spin structure indicates an unexpectedly strong spin-charge coupling in electron-doped cuprates. 相似文献
142.
Yuntao Wang Huaiyu Shao Yan Li Lei Xie Xingguo Li Seiki Takahashi 《Journal of magnetism and magnetic materials》2007
Hydrogen absorption properties of SmNiAl were systematically investigated between room temperature and 673 K over the pressure range from 0 to 10 MPa. It absorbs hydrogen without clear plateaus, forms hydride SmNiAlHx (x=0.75–2.04) without structural change below 623 K and decomposes into SmH2 and NiAl at higher temperatures. Then, the magnetic curves, the field-cooled (FC) and the zero-field-cooled (ZFC) susceptibilities of SmNiAl and its hydride were investigated. SmNiAl behaves as paramagnetic above 65 K, but has three antiferromagnetic transitions at lower temperatures. Hydrogenation enhances its magnetism, but weakens the interaction between magnetic moments. In the FC process, hydrogenation especially induces an anomalous diamagnetism. Mechanisms for the hydrogen absorption, structural change and magnetism were discussed. 相似文献
143.
We investigate the manifestation of stripes in the in-plane resistivity anisotropy in untwinned single crystals of La2-xSrxCuO4 ( x = 0.02-0.04) and YBa(2)Cu(3)O(y) ( y = 6.35-7.0). It is found that both systems show strongly temperature-dependent in-plane anisotropy in the lightly hole-doped region and that the anisotropy in YBa(2)Cu(3)O(y) grows with decreasing y below approximately 6.60 despite the decreasing orthorhombicity, which gives most direct evidence that electrons self-organize into a macroscopically anisotropic state. The transport is found to be easier along the direction of the spin stripes already reported, demonstrating that the stripes are intrinsically conducting in cuprates. 相似文献
144.
Yoshinori Tominaga Yoshiki Matsuoka Yukio Oniyama Yoshimitsu Uchimura Hirofumi Komiya Michiyo Hirayama Shinya Kohra Akira Hosomi 《Journal of heterocyclic chemistry》1990,27(3):647-660
Polarized ethylenes having both electron-donating (an amino or a methylthio group) and electron-accepting (cyano, carbamoyl, methyl ester) groups on the adjacent two olefinic carbon atoms were prepared by the condensation of S-alkylthioamidinium salts or methyl dithiocarboxylates with the corresponding active methylene compounds in good yields. These polarized ethylenes were alternatively synthesized by the reaction of thioamides or methyl dithiocarboxylates with tetracyanoethylene oxide in good yields. Reactions of these polarized ethylenes with hydrazine or guanidine derivatives occurred smoothly to give the corresponding pyrazole and pyrimidine derivatives in good yields. The synthesis of 5-aza[2.2.3]cyclazine derivatives using polarized ethylenes is also described. 相似文献
145.
The polarized infrared absorption due to the fundamental and 2nd-harmonic excitation of the localized vibration of Be in CdS and CdSe is observed. The splitting and the polarization property are in accord with C3ν point symmetry of Be impurity. The anharmonic potential coefficients are obtained up to the 3rd order. The Raman scattering from Be localized mode is also measured in the case of CdS: Be. 相似文献
146.
We report on the interlayer far infrared response for a series of La2-xSrxCuO4 crystals with 0.08相似文献
147.
Using infrared spectroscopy, we show that spin self-organization in untwinned La2-xSrxCuO4 (LSCO) crystals has profound consequences for the dynamical conductivity sigma(omega). The electronic response of CuO2 planes acquires significant anisotropy in the spin ordered state with enhancement of the conductivity along the direction of the diagonal spin stripes by up to a factor of 2. An examination of the anisotropic response indicates that the diagonal spin texture in weakly doped LSCO is also accompanied by the modulation of charge density. The electronic response of the charge stripes is found to be gapless consistent with the hypothesis of the metallic ground state. Our experiments directly show that the striped ordered systems reveal new degrees of freedom not present in ordinary one-dimensional conductors. 相似文献
148.
Oblatum 20-I-1993 & 19-VII-1993 相似文献
149.
150.
Hidetoshi Komiya 《Probability Theory and Related Fields》1982,61(1):119-128
Summary An infinite matrix is said to be doubly substochastic if it has nonnegative components and each row and each column sum is at most 1. Let x and y be two real sequences which converge to 0 or which are absolutely summable. This paper introduces necessary and sufficient conditions for existence of an infinite doubly substochastic matrix A such that x=Ay concerning partial order and convex hull for sequences. 相似文献