Vectorial mapping of exchange anisotropy in IrMn/FeCo multilayers using the reversible susceptibility tensor

Abstract

A method for probing exchange anisotropy based on reversible susceptibility tensor is proposed. The experimental results obtained on exchange biased IrMn/FeCo multilayers are supported by the theoretical analysis of the transverse and longitudinal susceptibilities in the case of exchange-coupled systems. The vectorial mapping of the exchange bias in the studied sample is performed by detecting a composite signal containing both transverse and longitudinal susceptibilities for different orientations of the applied field. This procedure, that is demonstrated both theoretically and experimentally, allows one to obtain the critical curve of the switching fields. The critical curve constitutes the fingerprint of the switching processes from which both magnitude and direction of the directional anisotropy can be determined.

Inter-particle interactions and magnetism in manganese–zinc ferrite nanoparticles

“…We have successfully applied this technique to several materials in thin-film form such as epitaxially grown CrO 2 thin films [12]. TS has also been used to study exchange biased IrMn/FeCo multilayers [13], fine-particle systems such as BaFe 12 O 19 [14], g-Fe 2 O 3 nanoparticles [15], Au-Fe core-shell nanoparticles [16] and magnetic recording media [17]. In a recent study, we had reported systematic TS measurements to resolve the nature of in-plane and out-of-plane dipolar interactions in multilayered nanoparticle arrays of Fe [18].…”

Physics of complex transverse susceptibility of magnetic particulate systems

“…Transverse susceptibility ͑TS͒ is one of the most sensitive methods in determining the magnetic anisotropy, and it was used with great success to characterize close-packed arrays of monodisperse Fe nanoparticles, 1 Fe͑001͒ square nanostructures, 2 exchange-biased IrMn/ FeCo multilayers, 3 epitaxial CrO 2 and CrO 2 /Cr 2 O 3 bilayer thin films, 4,5 and perpendicular recording media. Also, there is a great interest in describing theoretically the transverse susceptibility in magnetic nanosized systems.…”

“…Thus, some of the restrictions in the first theoretical approach of Aharoni et al 8 were overcome [10][11][12][13][14][15] and the increased sensitivity of new experimental TS methods allowed the investigations of magnetic systems with very low concentration of magnetic moments. 3,4,16,17 A very recent development of TS constitutes the complex TS. It was first mentioned by Papusoi 18 in the context of magnetic particulate systems and it spurred a lot of attention as it was presented as a new way to determine the particle volume and anisotropy field distributions of a particulate medium.…”

Generalized reversible susceptibility tensor

“…2,3 The theoretical study of transverse susceptibility ͑TS͒ was not subject to substantial changes after Aharoni's classical-article 2 in which the first comprehensive theoretical description of the reversible susceptibility tensor for the Stoner-Wolfarth model 4 was given. Subsequent theoretical approaches of TS overcame some limitations of Aharoni's approach by taking into account magnetic systems with different types of anisotropy, [5][6][7] or studying the effect of interactions 8 and thermal relaxation. 8,9 What is common to all papers published previously and dealing with transverse susceptibility modeling is the theoretical approach used.…”