BINDING OF HOLES TO MAGNETIC-IMPURITIES IN A STRONGLY CORRELATED SYSTEM

The effect of a magnetic (S = 1/2) impurity coupled to a two-dimension al system of correlated electrons (described by the t-J model) is stud ied by exact diagonalizations. It is found that, if the exchange coupl ing of the impurity with the neighboring spins is ferromagnetic or wea kly antiferromagnetic, an extra hole can form bound states of differen t spatial symmetries with the impurity extending to a few lattice spac ings. The binding energy is maximum when the impurity is completely de coupled (vacancy) and vanishes for an antiferromagnetic coupling excee ding similar to 0.3J. Several peaks appear in the single-hole spectral function below the lower edge of the quasiparticle band as signatures of the d-, s-, and p-wave bound states.