Comparison between micromagnetic simulation and experiment for the Co∕γ-Fe50Mn50 exchange-biased system

Abstract

We have constructed a micromagnetic model to study the exchange coupling between Co (a ferromagnet) and γ-Fe50Mn50 (an antiferromagnet) in a thin film bilayer with (111) texturing. The intention is to compare experimental results with a micromagnetic calculation that is sufficiently sophisticated to realistically model this polycrystalline ferromagnet/antiferromagnet system. The antiferromagnet thickness dependences of exchange bias and enhanced coercivity were simulated at 10 and 300K and comparison to experiments revealed reasonable agreement. We also examined the antiferromagnet grain size dependence of exchange bias, owing to its relation to the key issue of uncompensated spin density. Simulation finds a linear relationship between exchange bias and inverse grain size for both thermally stable and thermally fluctuating antiferromagnetic grains, but with different intercepts. Experiment also finds a linear dependence, but the extrapolation to infinite diameter reveals an unexpected negative exchange bias. Our results demonstrate the applicability of this form of micromagnetic modeling for multiple phenomena associated with the exchange bias effect.

High-frequency response of nanostructured magnetic materials

“…These results highlight the role of the exchange bias for controlling the dynamic behavior of the dot. The key point is a fine description of the exchange bias coupling in close relation with the interfacial nanostructure [82,83].…”

Asymmetric magnetization reversal in a single exchange-biased micro bar

“…Such an element has dimensions achievable by calcula- tions using micromagnetic simulations. [19] The magnetoresistance measurements exemplify the asymmetry in the reversal, whereas the magnetic force microscopy images show the distribution of the magnetic domains at different stages of the reversal. Unlike vibrating sample magnetometry (VSM) or SQUID measurements, the AMR measurements can be performed on particles with magnetic moments under 10 −9 emu.…”