Coarsening of Antiferromagnetic Domains in Multilayers: The Key Role of Magnetocrystalline Anisotropy

Abstract

The domain structure of an antiferromagnetic superlattice is studied. Synchrotron Mössbauer and polarized neutron reflectometric maps show micrometer-size primary domain formation as the external field decreases from saturation to remanence. A secondary domain state consisting mainly of at least 1 order of magnitude larger domains is created when a small field along the layer magnetizations induces a bulk-spin-flop transition. The domain-size distribution is reproducibly dependent on the magnetic prehistory. The condition for domain coarsening is shown to be the equilibrium of the external field energy with the anisotropy energy.

Stroboscopic detection of nuclear resonance in an arbitrary scattering channel

“…Preparation and characterization of the MgO(001)/[ 57 Fe/Cr] 20 multilayer sample has been described earlier Nagy et al, 2002;Tanczikó et al, 2004). The layering was verified as epitaxial and periodic, with thicknesses of 2.6 nm for the 57 Fe layer, and 1.3 nm for the Cr layer.…”

Nuclear resonant scattering of synchrotron radiation: Applications in magnetism of layered structures

“…From surface sensitive measurements it is well known that ferromagnetically coupled magnetic multilayers exhibit a striped domain configuration while the antiferromagnetic coupling often bears a patch-like pattern [31]. Off-specular nuclear scans can now, very similar to those with polarized neutrons, be performed to study the domain configuration within the multilayer stack [32]. Fig.…”

Simulation of Antiferromagnetic Domain Formation History in Magnetic Multilayers

“…Introduction Antiferromagnetically (AF) coupled metallic multilayers (ML) show giant magnetoresistance (GMR) effect [1]. Recently a domain tailoring mechanism was found on an AF-coupled Fe/Cr ML with fourfold in-plane anisotropy by off-specular synchrotron Mö ssbauer reflectometry (SMR) and verified by polarised neutron reflectometry (PNR) [2]. Small (mm size) domains form when the external magnetic field H ext is decreased from the saturation to remanence.…”

“…Easy-axis and hard-axis scenarios are qualitatively different. In our model [2] we associate the domain formation and coarsening with the effective correlation length of the saturation field H sat and that of the spin-flop field H sf , respectively. Unsaturating the sample along an easy axis down to remanence leads to a single stable configuration with the magnetisations perpendicular to the field.…”