The influence of interface structure on the magneto-optical properties of Co/Pd multilayers

Abstract

Magneto-optical Kerr effect (MOKE) spectra of Co/Pd multilayered structures (MLS), measured in the polar geometry over the spectral range 0.8-5.5 eV, are presented and compared to spectra obtained from ab initio band-structure calculations. It is shown that the MOKE spectra of the Co/Pd MLS calculated using the spin-polarized relativistic linear-muffin-tin-orbital method reproduce the experimental spectra only moderately well if ideal multilayer structures with sharp interfaces are assumed. Calculations of the magneto-optical (MO) response of MLS with imperfect interfaces modelled by introducing ordered compounds at the interface have also been performed. The results obtained reveal that the MOKE spectra of the Co/Pd MLS can be adequately reproduced using a model of limited interdiffusion within one or two atomic planes at the interface which results in the formation of a Pd-rich alloy. The role of the Pd spin polarization in the formation of the MO spectra as inferred from first-principles calculations is examined and discussed. Finally, the influence of thermal annealing on the MO properties of Co/Pd MLS is studied both experimentally and theoretically. The good agreement between the calculated spectra of the MLS and experimentally observed ones demonstrates the validity of the proposed models. The results obtained demonstrate the crucial role played by the interface microstructure in the formation of the MOKE spectra of the multilayered systems studied.

Correlation of structure and magnetism of ultrathin Co films on Pd(001) prepared by thermal and pulsed laser deposition

“…However, the magnetic moments of Pd obtained in our study are systematically larger as reported in Ref. 48, where Co/ Pd multilayers were studied using unrelaxed interlayer fcc-Pd distances ͑1.945 Å͒. In contrast to this work, our SXRD analysis shows that the distances between the Co and Pd layers are smaller by 10%-15%, leading to a stronger hybridization and to a larger polarization of the Pd atoms.…”

“…Pd atoms in proximity to Co atoms acquire a finite magnetic moment in agreement with other theoretical studies. 48 Magnetic moments are at a maximum ͑up to 0.38 B ͒ in Pd layers adjacent to Co layers and within the Co x Pd 1−x alloy layers, but rapidly decrease along the direction into the interior of the crystal.…”

“…The experimental evidence for a negative polar Kerr rotation detected for Co atoms in a Pd-rich environment is supported by ab initio band-structure calculations for the Co/ Pd multilayer structure. 48 When the contribution from the noninterface part of the film dominates, the polar MOKE loops change sign and become normal ͓above a thickness of 2.7 ML in the case of Co grown on Pd͑001͔͒.…”

A mode-of-growth-dependent magneto-optical response from ultrathin Co films on Pd surfaces

“…2(a)) should be seen in the polar MOKE as well. The negative polar Kerr rotation measured for the Co/Pd interface agrees with the available theoretical calculations performed for Co/Pd multilayers [11]. The calculations show that for the experimental photon energy of 1.84 eV the polar Kerr rotation depends strongly on the multilayer composition, changing sign for the thinnest Co layers.…”

Electronic Structure of Strongly Correlated Systems

“…Prototype studies have been performed using modern methods of band theory for Fe, Co, and Ni [55][56][57][58][59]. Following the calculations for the elemental 3d ferromagnets, a number of groups have evaluated the MO and XMCD spectra for more interesting compounds [10, and multilayers [89][90][91][92][93][94][95][96][97][98][99][100][101][102].…”