Estudo das propriedades termodinâmicas no modelo de Ising aleatoriamente decorado com interações competitivas

Abstract

In this work we will study the thermodynamics properties of the quenched decorated Ising model with competitive interactions through the effective field theory (EFT) of a one-spin cluster. The quenched decorated Ising model with competitive interactions is here used to describe the thermodynamics properties of the cooper-based oxide superconductors compounds in the insulating phase (antiferromagnetic). The model consists of planes in which the nodal spins interact antiferromagnetically (JA < 0) with their nerest-neighbors and ferromagnetically (JF > 0) with the spins that decorated the bonds, which are quenched randomly distributed over the twodimensional lattice. The planes interact antiferromagnetically with weak exchange interaction (i.e., JA´=λ JA , λ=10-5 ). By using the framework of an effective-field theory, based in the differential operator technique, we discuss beyond thermodynamics properties the antiferromagnetic-phase stability limit in the temperature-decorated bond concentration space (T-p), for λ =10-5 and various values of frustration parameter (α= JA / JF), magnetic field (H) and concentration parameter (p). For certain range of the parameter α we observe a reentrant behavior in low-temperature what it reflects in the properties behavior itself.