6,885 research outputs found
Progressive evolution of tunneling characteristics of in-situ fabricated intrinsic Josephson junctions in Bi_2Sr_2CaCu_2O_{8+delta} single crystals
Stacks of a few intrinsic tunnel junctions were micro-fabricated on the
surface of Bi-2212 single crystals. The number of junctions in a stack was
tailored by progressively increasing the height of the stack by ion-beam
etching, while its tunneling characteristics were measured in-situ in a vacuum
chamber for temperatures down to ~13 K. Using this in-situ etching/measurements
technique in a single piece of crystal, we systematically excluded any spurious
effects arising from variations in the junction parameters and made clear
analysis on the following properties of the surface and inner conducting
planes. First, the tunneling resistance and the current-voltage curves are
scaled by the surface junction resistance. Second, we confirm that the
reduction in both the gap and the superconducting transition temperature of the
surface conducting plane in contact with a normal metal is not caused by the
variation in the doping level, but is caused by the proximity contact. Finally,
the main feature of a junction is not affected by the presence of other
junctions in a stack in a low bias region.Comment: 25 pages, 7 figures, submitted to Phys. Rev.
Charlene J. Sato's "Language Change in a Creole Continuum: Decreolization?"
This article is on the process of decreolization in individuals and in social context. It focuses on decreolization from linguistic and sociolinguistic aspects ofthe Hawai'i creole continuum. Sato begins her article by defining the main concept 'decreolization' as "the process through which a creore language gradually merges with its lodfier ranguage, i.e., the standard language ofthe community, as a result ofcreole speakers' increased access to and 'targeting' ofthe latter" (sato, 199r, p. r22). The study of this process is useful because it can reveal the consequences of language contact and the nature of language change
Suppressed Superconductivity of the Surface Conduction Layer in BiSrCaCuO Single Crystals Probed by {\it c}-Axis Tunneling Measurements
We fabricated small-size stacks on the surface of
BiSrCaCuO (BSCCO-2212) single crystals with the bulk
transition temperature 90 K, each containing a few intrinsic
Josephson junctions. Below a critical temperature ( ), we have
observed a weakened Josephson coupling between the CuO superconducting
double layer at the crystal surface and the adjacent one located deeper inside
a stack. The quasiparticle branch in the data of the weakened Josephson
junction (WJJ) fits well to the tunneling characteristics of a d-wave
superconductor()/insulator/d-wave superconductor (DID) junction. Also,
the tunneling resistance in the range agrees well with the
tunneling in a normal metal/insulator/d-wave superconductor (NID) junction. In
spite of the suppressed superconductivity at the surface layer the symmetry of
the order parameter appears to remain unaffected.Comment: 13 pages, 6 figure
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