We develop a general theory for the local environment of a magnetic impurity in a superconductor, using an Anderson model to describe the impurity. We can thus cover many regimes (i.e, Kondo, mixed valence) of physical interest. A general formula expressing the perturbed order parameter, δΔ(q), in terms of the impurity t matrix is derived; this formula is then used to derive a simple expression, valid as T→${\mathit{T}}_{\mathit{c}}$, relating the total volume integral of δΔ(r) to the change in ${\mathit{T}}_{\mathit{c}}$ with impurity concentration. Finally, explicit curves for δΔ(r) are computed for the Hartree-Fock limit.

• Received 1 February 1993

DOI:https://doi.org/10.1103/PhysRevB.48.3933