Work

NQR study of local structures and cooling rate dependent superconductivity in La sub 2 CuO sub 4+. delta

Year: 1992

Type: conference-paper

Abstract: Structural properties of oxygen-annealed polycrystals of La{sub 2}CuO{sub 4 + {delta}} ({delta}{approximately}0.03) have been studied using {sup 139}La NQR spectroscopy. Superconducting critical temperatures were found to depend on the rate of cooling through a narrow temperature range at about 195K. Preliminary analysis of the {sup 139}La NQR spectra suggest that the oxygen-rich phase-separated region is composed of two structurally distinct phases, both of which are metallic and super-conducting. One phase has a structure closely related to the stoichiometric oxygen-poor compound. The second shows a considerable amount of apical oxygen disorder, a large shift in NQR frequency {nu}{sub Q}, and a volume fraction which increases with cooling rate. The formation of the second phase below {minus}200K is indicative of the freezing Of CuO{sub 6} octahedral tilting. Abrupt shifts in {nu}{sub Q} above {Tc} were also observed for both phases, suggestive of a local structural anomaly or charge transfer to the Cu-O plane.

Source: University of North Texas Digital Library (University of North Texas)

Authors: Reyes, A. P., Ahrens, E. T., Hammel, P. C., Heffner, R. H., Thompson, J. D., Canfield, P. C., Fisk, Z., Schirber, J. E.

Institutions: Los Alamos National Laboratory, Sandia National Laboratories California, Sandia National Laboratories

Language: English

Topic: Physics of Superconductivity and Magnetism

Subfield: Condensed Matter Physics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: green

Funder: U.S. Department of Energy

OpenAlex ID: W3012564421

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