Magnetic profile as a function of structural disorder in Fe/Cr superlattices

Abstract

Structural disorder has been systematically introduced in an [Fe(30 Å)/Cr(17 Å)]10 superlattice to investigate its effects on the magnetization profile. Low angle x-ray and neutron scattering results indicate progressive structural degradation in samples produced with increased argon pressure (3, 6, and 12 mTorr). The x-ray spectra from the more disordered samples are characterized by a decreased intensity and increased linewidth of the superlattice Bragg peaks, along with a systematic disappearance of the finite size intensity oscillations. Elastic, polarized, low angle, neutron reflectivity data exhibit decreasing superlattice Bragg intensities and increasing linewidths, indicating increased disorder in agreement with x-ray data. Antiferromagnetic alignment of adjacent Fe layers is inferred by the appearance of magnetic peaks between the structural peaks and by the lack of magnetic contribution to the structural superlattice peaks. Interestingly, the magnetic superlattice peak does not exhibit appreciable degradation with increasing disorder in the structure, indicating a magnetic coherence length significantly greater than that of the chemical superlattice structure.