Magnetic impurities in d-wave superconductors

We solve the problem of a magnetic impurity in a d(x2-y2)-wave superconductor by a variational method. A moment is found to exist in the superconducting state only if the Kondo temperature in the normal state is larger than the maximum in the superconducting gap function. If a moment exists in the superconducting state, and provided spin-orbit coupling is nonzero, it induces a time-reversal breaking superconducting state locally around the inpurity which is a linear combination of the d(x2-y2) and d(xy) states. The current pattern around the impurity in this state is evaluated. [S0163-1829(99)06137-8].