Renormalization-group magnetization of a ferrimagnetic Ising system

We employ a real-space renormalization-group (RSRG) approach to study a mixed-spin (spin- and spin-1) antiferromagnetic Ising model on the square lattice. The model incorporates next-nearest-neighbor interactions which are relevant to describe ferrimagnetism. We present an RSRG calculation of the spontaneous magnetization and compensation temperatures of the mixed-spin model. The influence of crystal-field and next-nearest-neighbor interactions on compensation temperatures is studied; the important physical ingredient that leads to the presence of these temperatures is the next-nearest-neighbor coupling between spins .