Study of magnetic anisotropy and induced spin polarization in FE/CO/CU3AU(001): an experimental and first-principles investigation

Abstract

Understanding the complex correlations structure-magnetism and the origins of the magnetic anisotropy in ultrathin magnetic heterostructures is an active research area in physics, given its great potential for new technologies in data storage and processing, and devices. In this work we investigated the induced magnetization of interfacial Cu atoms in ferromagnetic Fe/Co ultrathin films grown on an fcc Cu3Au(001) substrate. To explore the interfacial nature of the induced magnetic moments and its origin, we probed two structures of five alternate Fe and Co monoatomic layers with either Fe or Co in direct contact with the nonmagnetic Cu3Au(001) surface. X-ray magnetic circular dichroism measurements at the L2,3 edges of Fe, Co and Cu allowed to extract the spin and orbital magnetic moments of Fe and Co in both structures, and to measure extremely low magnetic moments induced in Cu atoms. The samples were grown and probed in-situ at the PGM beamline. The same systems were also investigated by first principles calculations, in order to obtain the spin and orbital moments of the different atoms for both Fe-Co/Cu3Au(001) stacks, disentangling the origin of magnetic proximity effects at these ferromagnetic/non-magnetic interfaces. The experimental and theoretical results reveal an induced magnetism only in atoms at the interface layer of the ordered Cu3Au(001) substrate, i.e., the observed Cu XMCD signal is due to only 0.5 ML magnetic Cu atoms. Such results clearly demonstrate the importance of the structural, electronic, and magnetic interface reconstructions on the appearance of magnetic induced moments, which at the end determine the detailed behavior of the magnetic anisotropy.