NONUNIVERSAL CRITICAL-BEHAVIOR IN PLANAR ISING-MODELS WITH EXTENDED, RADIALLY SYMMETRICAL DEFECTS

Using conformal mapping and finite-size scaling we determine the local magnetic exponent near a defect characterized by couplings of the form J(r) = J(1+A/r)). In accordance with phenomenological considerations, we find that it depends continuously on the amplitude A, both for a defect in the interior and on the boundary.