Magnetic behavior of a diatomic molecule with spin-1 on the Bethe lattice

Abstract

Thermal fluctuations in magnetizations and magnetic phase diagrams of a diatomic molecule are investigated on the Bethe lattice (BL) with coordination number q=3 by using the exact recursion relations (ERR). Each molecule is assumed to interact with others via its atoms in terms of various bilinear interaction parameters. They involve the interaction of atoms within each molecule as well as the interaction of atoms between the molecules. Each site is also considered to have an active crystal field. Following the determination of the average magnetization of the molecule and its atoms in the central molecule of the BL in terms of ERR, their thermal fluctuations and potential phase diagrams are thoroughly analyzed. Numerous phase regions, ordered (O), i.e., ferromagnetic (FM) or antiferromagnetic (AFM), paramagnetic (P), and random (R), are discovered. The phase boundaries between these phases are obtained in terms of first- and second-order and random phase transition lines. Therefore, various critical phenomena, including tricritical point (TCP), bicritical point (BCP), critical end point (CEP) and reentrant behavior (RB), are observed.