College Park, Maryland      June 6 - 10 , 2004

WP18: Structure of potentially superconducting silver fluorites

S. Mclain (University of Tennessee; Argonne National Laboratory), J. Turner (University of Tennessee), T. Proffen (Los Alamos National Laboratory), M. Dolgos (University of Tennessee)

High temperature superconducting cuprates have been investigated extensively in recent years. Spin-1/2 ions that possess similar or identical structural chemistry to the Cu(II) ions in the high Tc cuprates are rare. One such ion is Ag(II), which, being unstable in an oxide lattice context is stable in various fluoride phases, that are structurally analogous to the 214 Ag2CuO4. Here we present the results of neutron scattering studies on the fluoride-based 214 analog Cs2AgF4, which displays the strongly correlated spin interactions expected of a S=1/2 ion in a structure similar to that of K2CuF4.

Understanding of these materials obviously requires a detailed understanding of the atomic structure. It has become more and more apparent that structure analysis based on Bragg intensities alone gives an incomplete picture, completely ignoring disorder or the local structure of these materials. One approach to extract local structural information from the total scattering pattern, i.e. Bragg and diffuse scattering, is the Pair Distribution Function (PDF) method. Much progress has been made understanding the local structure of cuprates using the PDF [1].

Variable temperature neutron diffraction studies on NPDF at LANSCE over a Q range of 50 A-1 have allowed both Bragg analysis of the long range order and pair distribution function (PDF) analysis of the local structure of this material. The structure and the temperature behavior of the structure will be presented and parallels drawn with similar PDF studies on structurally related cuprate and manganite materials.

[1] E. S. Bozin, S. J. L. Billinge, H. Takagi and G. H. Kwei, Neutron diffraction evidence of microscopic charge inhomogeneities in the CuO2 plane of superconducting La2-xSrxCu4 ( 0<= x<= 0.30), Phys. Rev. Lett. 84, 5856 (2000).

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