Ka. Park et R. Joynt, PHOTOEMISSION AND TUNNELING AS TESTS FOR FLUCTUATING SUPERCONDUCTIVITY ABOVE T(C) IN HIGH-T(C) SUPERCONDUCTORS, Physical review. B, Condensed matter, 48(22), 1993, pp. 16833-16836
We examine the hypothesis that fluctuating local superconducting order
exists well above the critical temperature in high-T(c) materials. Th
is might explain anomalies in the magnetic susceptibility of some of t
hese systems. It could also create a gap or pseudogap in the density o
f states, which could be measured by photoemission or tunneling experi
ments. We compute the density of states for a two-dimensional tight-bi
nding model with such local order in the coherent-potential approximat
ion. The order parameter is taken to have a spatially random phase and
constant magnitude. We calculate this magnitude by a Ginzburg-Landau
method. The conclusion is that the disorder smooths out the gap in the
density of states unless the local order parameter is larger than the
zero-temperature gap.