was investigated along with structural analysis in terms of pair distribution function (PDF). The low activation energy, $1.2 eV, for diffusion in the oxides suggests a single atomic jump of oxygen ions mediated via vacancy-like defects. However, the pre-exponential factor for a-Ta 2 O 5 and a-Nb 2 O 5 with lower bond energy was two orders of magnitude larger than that for a-Al 2 O 3 with higher bond energy. PDF analyses revealed that the short-range configuration in a-Ta 2 O 5 and a-Nb 2 O 5 was more broadly distributed than that in a-Al 2 O 3 . Due to the larger variety of atomic configurations of a-Ta 2 O 5 and a-Nb 2 O 5 , these oxides have a higher activation entropy for diffusion than a-Al 2 O 3 . The entropy term for diffusion associated with short-range structures was shown to be a dominant factor for diffusion in amorphous oxides. V C 2014 AIP Publishing LLC. [http://dx

No abstract

No abstract

the normal state which has been proposed by theoreticians. We have succeeded in detecting the coherent Bose species in the normal state of YBa 2 Cu 3 O y . The idea ͓L. P. Levy, G. Dolan, J. Dunsmuir, and H. Bouchiat, Phys. Rev. Lett. 64, 2074 ͑1990͔͒ of having the detected oscillation of a fermion persisting current caused by the Aharanov-Bohm effect on magnetic field scanning in the assemblage of the mesoscopic rings of metal was employed in the assemblage of a ring patterned in the YB 2 Cu 3 O y film. The sensitivity of our detection system is not high enough to detect fermions, but it is high enough for detecting coherent bosons if they exist. Oscillations with flux periods corresponding to h/2e have been found at TϾTc, even at temperatures 30 K or more above T c inserted in the patterned YBa 2 Cu 3 O y film, but have not been found in the patterned Au or Pd films. To explain the coherent current circulating in a ring with a circumference as long as 40 m, presumably in the prestage to the superconducting stage, the possible coexistence of a minority of coherent bosons and a majority of incoherent bosons is discussed. The detection of minority coherent bosons in the background of a majority of incoherent species is possible in this method.