The exchange bias phenomenon in uncompensated interfaces: theory and Monte Carlo simulations

O V BILLONI; S A CANNAS; F A TAMARIT

JOURNAL OF PHYSICS CONDENSED MATTER

IOP PUBLISHING LTD

Año: 2011 vol. 23 p. 386004 - 386004

0953-8984

We performed Monte Carlo simulations of a bilayer system composed of two thin films, one ferromagnetic (FM) and the other antiferromagnetic (AFM). Two lattice structures for the films were considered: simple cubic and body centered cubic (bcc). We imposed an uncompensated interfacial spin structure in both lattice structures; in particular we emulatedan FeF2?FM system in the case of the bcc lattice. Our analysis focused on the incidence of the interfacial strength interactions between the films, Jeb, and the effect of thermal fluctuations on the bias field, HEB. We first performed Monte Carlo simulations on a microscopic model basedon classical Heisenberg spin variables. To analyze the simulation results we also introduced a simplified model that assumes coherent rotation of spins located on the same layer parallel to the interface. We found that, depending on the AFM film anisotropy to exchange ratio, the biasfield is controlled either by the intrinsic pinning of a domain wall parallel to the interface or by the stability of the first AFM layer (quasi-domain wall) near the interface.