Resolving antiferromagnetic states in magnetically coupled amorphous Co-Si-Si multilayers by soft x-ray resonant magnetic scattering

摘要

Soft x-ray resonant magnetic scattering (SXRMS) has been used to probe the interlayer coupling in amorphous ferromagnetic/semiconductor multilayers. It is shown that the [Co_(73)Si_(27) (50 A)/Si (30 A)] system exhibits an antiferromagnetic (AF) coupling at low fields. Moreover, another aspect of SXRMS effect is reported. Using circularly polarized photons, a shift in the AF order Bragg peaks' position is observed and related to two opposite AF states with the spin direction longitudinally aligned. As a consequence, the sensitivity of SXRMS to AF domains having the same spin axis but opposite senses is shown. A physical explanation for the origin of this effect is provided in terms of magnetic-resonant-refraction corrections to Bragg's angle, taking into account the phase shifts between layers with opposite magnetization directions at different in-depth positions. Numerical simulations are performed that reproduced the experimental observations.