THEORY OF THE REENTRANT TRANSITION IN A LAMELLAR ANTIFERROMAGNET - DOPED LA2CUO4

The effect of impurity-induced states on the long range order in a lamellar antiferromagnet (AF) is studied and the magnetic phase-diagram of a lightly doped La2-xSrxCuO4 is proposed. It is shown that long range magnetic perturbations and the layered structure cause the shrinkage of AF domain on the phase diagram and lead to the reentrant AF transition. A nonmonotonous dependence of the correlation length ξ2 D on temperature T is obtained; the dependence ξ2 D(x) is exponential for high T and ξ2 D∼x1/2 for low T. © 1990 Springer-Verlag.