Mean-field simulation of metal oxide antiferromagnetic films and multilayers

摘要

In this work the magnetization in antiferromagnetic thin films and multilayers with interlayer exchange coupling is simulated using mean-field approximation.Transition-metal oxide antiferromagnets are modeled as multiplane magnetic systems with 1 to 11 planes and the magnetization M is calculated as a function of temperature T.The antiferromagnetic films exhibit ferromagnetism when the number of monolayers is odd, i.e., when there is an uncompensated plane, but the net magnetization is lower than that of any single uncompensated plane due to cancellations and finite-size effects.With increasing film thickness the Neel temperature increases monotonically and the magnetic moment near the surface is reduced compared to that of the core, changing the form of the M(T) curve.When antiferromagnetic films are exchange coupled to each other, as in a multilayer with a nonmagnetic intervening layer, the surface magnetization of each film increases and the ferromagnetism of odd-numbered systems is enhanced.These results are shown to be experimentally testable by comparing magnetometry and neutron diffraction.