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Shigeki Miyasaka Akira Takemori Shin-nosuke Suzuki 《Journal of Physics and Chemistry of Solids》2011,72(5):414-417
We have investigated the relation between the temperature-dependence of resistivity and superconducting transition temperature Tc in RFeP1−xAsxO0.90F0.10 (x=0-1.0) (R=La and Nd). In contrast to the linear change of the crystal structure with increasing x, the temperature dependence of resistivity and Tc show non-monotonous x-dependence. When the As concentration x is increased, the temperature-dependence of resistivity changes from T2 to T-linear, and Tc distinctly increases in all the La compounds and the Nd ones with x<0.60. The results indicate that the substitution of As for P induces the spin fluctuation and resultantly enhances Tc. On the other hand, we could not find any relation between the temperature-dependence of resistivity and Tc in the Nd samples with x>0.60. This may suggest the existence of other parameters for determining Tc besides the antiferromagnetic correlation in this system. 相似文献
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Dynamic bulk and shear relaxation in glassy polymers. I. Experimental techniques and results on PMMA
In this paper the authors describe in detail the experimental techniques for the simultaneous measurement of the dynamic Young's modulus and the dynamic Poisson's ratio, from which the dynamic bulk and shear moduli can be calculated. Experimental results are presented on the effects of temperature, frequency, and tensile strain on these properties of poly(methyl methacrylate) (PMMA). The temperature and frequency effects indicate that the β relaxation in PMMA is not a purely internal motion but is coupled to the bulk. 相似文献
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Kawai N Inoue K Carlsson N Ikeda N Sugimoto Y Asakawa K Takemori T 《Physical review letters》2001,86(11):2289-2292
The transmittance spectrum for an air-bridge type of AlGaAs photonic crystal (PC) slabs successfully fabricated was measured. It is found that the observed spectrum is consistent with both the theoretical band structure and the calculated one. Moreover, the transmittance due to the modes below the light line is found to be almost 100%, indicating that the guided modes should exist. The respective stop bands are observed in the gamma-M direction for TM-like and TE-like modes, implying that a photonic band gap should exist for the TE-like guided modes. The present PC is very suited for controlling the radiation field. 相似文献
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Carlsson N. Ikeda N. Sugimoto Y. Asakawa K. Takemori T. Katayama Y. Kawai N. Inoue K. 《Optical and Quantum Electronics》2002,34(1-3):123-131
Selective wet etching is a technique that allows fabrication of freely suspended thin slabs in epitaxial heterostructures. This technique, together with high-aspect ratio dry etching, is used to create two-dimensional (2D) photonic crystals for near-infrared wavelengths in thin suspended AlGaAs membranes. The active photonic crystal areas contain hexagonal arrays of cylindrical holes completely perforating the membrane. For an appropriate selection of the slab thickness and the lattice parameter, dispersion relations for the guided modes are explicitly computed by solving the Maxwell equations in a geometry containing a 2D photonic crystal defined in the core layer of a dielectric waveguide structure. Measurements of the spectral transmittance in air-bridge samples show a narrow 30-dB-deep stop band for TM polarized incident light. The spectral position of the stop band shows a good agreement with theoretical band structure calculations when also the quasi-guided resonant modes outside the light cone are taken into account. 相似文献
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Mathematische Zeitschrift - We correct the proof of the theorem in the previous paper presented by Kikuta, which concerns Sturm bounds for Siegel modular forms of degree 2 and of even weights... 相似文献
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Real-time measurements of in-plane vibrations by speckle interferometry, which employs a liquid crystal light valve to record speckle patterns, is experimentally studied to be feasible in practice, and preliminary results are also shown. 相似文献
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Electron-electron interactions in Anderson-localized states lead to both ferromagnetic (direct exchange) and antiferromagnetic (kinetic-type exchange) interactions among spins of singly occupied states. Specific heat anomaly, in particular its magnetic field dependence, and magnetic susceptibility at low temperatures are calculated by taking into account the coexistence of ferromagnetic and antiferromagnetic interactions among localized spins within a pair model. It is shown that the experimental results on Si:P can be well explained by the present theory. 相似文献