Role of noncollinearity of Cr magnetic moment distribution in Fe/Cr superlattices

Formation of noncollinear distribution of the magnetic moments in Fe/Cr(001) and Fe/Cr(110) superlattices with ferromagnetic coupling of the Fe slabs having abrupt interfaces are considered in noncollinear Anderson model approach. Self-consistent calculations for variable Cr spacer thickness from 1 to 9 monolayers are carried out using a total-energy minimization for arbitrary orientations of the Fe and Cr magnetic moments in a given plane. It is found that the Fe/Cr(001) superlattices with Cr spacer from 6 to 9 monolayers decrease their total energy for a quasi-helicoidal distribution of the magnetic moments which consists in two interleaved spirals. Magnetic moments distribution in the Fe/Cr(110) superlattices decrease their total energy for noncollinear ordering in the Cr spacer with number of monolayers from 5 to 9. The moments of atoms at the interfacial Cr layers are canted to each other with the values reduced to 0.15-0.17 mu(B), whereas the Cr moments in the intermediate monolayers drastically reduce their values to 0.04-0.06 mu(B) having an opposite orientation of the moments with a polarization plane perpendicular to the Fe slabs.