Microscopic origin of the magneto-optical properties of CoPt alloys

Abstract

The microscopic origin of the magneto-optical ͑MO͒ properties of Co x Pt 1Ϫx alloys is studied on the basis of Kerr effect measurements and first-principles band-structure calculations in a wide range of photon energy (បϭ0.75-5.8 eV) and Co content (xϭ0.03-0.5). Spin-polarized relativistic linear-muffin-tin-orbital ͑LMTO͒ calculations performed within the local density approximation and supercell approach reproduce well the spectral shape of the measured off-diagonal optical conductivity tensor components. Using the ab initio LMTO band-structure calculations, the band-by-band and k-space decompositions as well as the analysis of the magneto-optical transitions between electronic states localized in different energy regions are performed. It is found that for the alloys studied the uv part of the MO spectra with a pronounced peak at 4 eV photon energy comes from optical transitions between initial and final states located within well-defined energy intervals that are very close to those obtained for fcc Pt metal in external magnetic field. The correlation between the band structure of the alloys and the energy dependence of their MO spectra is investigated. The importance of the spin-orbit interaction for the transitions in different energy regions is demonstrated by calculating the state-and site-projected density of the expectation value of the orbital moment. The evolution of the electronic structure of Co-Pt alloys with the increase of Co content and the influence of the hybridization between the Co and Pt electronic states are analyzed and discussed.

Femtosecond Spectrotemporal Magneto-optics

“…We used this technique for studying the spectral and temporal dependence of the MO contrast in a CoPt 3 sample. The results show that a slight spectral dependence is present in the static MO response as already demonstrated in previous studies [26,27]. On the contrary, the dynamical behavior of the relative variations of rotation and ellipticity are identical and do not show any spectral dependency.…”

Structure, magnetic and magneto-optical properties of La-Ca-Co substituted strontium ferrites

“…6 and Table 1). The general shape of the spectra is similar to that reported by Heczko et al 29,30 , no relevant transitions are observed below 2 eV and the main transitions are located at 2.4, 3.0 and 3.8 eV, in agreement with Ref. [29].…”

Magnetic anisotropy and microstructure in sputtered CoPt(110) films

“…This is one of the highest anisotropy energies predicted in transition metal alloys and results from the spin polarization of the Pt 5d band combined with the spin-orbit [6][7][8][9] coupling on Pt. These systems are particularly interesting for magneto-optic [10] recording because they exhibit large Kerr [11] effect signals and because they are chemically stable.…”