Interface exchange parameters in La2/3Ca1/3Mn3O/La1/3Ca2/3Mn3O bilayers: a Monte Carlo approach

Abstract

Ferromagnetic/antiferromagnetic (FM/AF) bilayers have been widely studied because they exhibit special phenomena, such as exchange bias and magnetoresistance. These effects are strongly influenced by interface behavior. In this work, a study of hysteresis loops in La2/3Ca1/3MnO3/La1/3Ca2/3MnO3 bilayers is presented. Simulations were carried out using the Monte Carlo method combined with the Metropolis algorithm and Heisenberg model. The study was focused on determining the most suitable exchange parameters at the interface by applying the model proposed by Kiwi. This model considers the use of two interface exchange parameters to represent the anisotropy that occurs at the interface because of the contact between two phases (ferromagnetic and antiferromagnetic). These two interface exchange parameters were named JI1 and JI2. Initially, we assumed JI1 to be equal to JI2 without presenting exchange bias. Then, JI1 and JI2 were assumed to be different. In this configuration, the exchange phenomenon appeared in the hysteresis loops. It was also observed that the exchange bias is strongly dependent on the ratio of JI1 to JI2. As JI1 increases, the exchange bias decreases slowly and becomes comparable to the effective exchange bias field, assuming that it only depends on ΔJI=JI1−JI2.