EFFECTS OF A MAGNETIC-FIELD AND SUPERCONDUCTING PAIRING ON MAGNETIC EXCHANGE IN METALS

The indirect exchange interaction between moments in a metal mediated by the conduction electrons is discussed. In a disordered normal metal owing to the long diffusion paths a magnetic field has an important effect on the second moment of the interaction. In a superconductor the interaction decreases exponentially with distance if the gap is isotropic but is a power law if the gap has nodes. For singlet pairing the interaction has the Heisenberg form while for triplet pairing it depends on the symmetry of the gap function. © 1990.