Indirect exchange interaction in lead salts

The indirect exchange interaction between magnetic ions embedded in a lead salt host lattice, mediated by the spin-dependent polarization effects, is theoretically studied. It is found that the interaction is ferromagnetic in sign and greatly enhanced in strength because of the multivalley band structure of the host material. The interaction decays exponentially with the interspin distance, and the decay constant is determined by the energy gap and the effective masses of the electron and the hole. A recent experiment in Pb_1-xMnₓTe is also briefly discussed.