A. Ya. Perlov

Calculated magneto-optical Kerr spectra of compounds (X = V, Cr, Mn, Fe and Co)

The magneto-optical spectra of the compounds (with X = V, Cr, Mn, Fe and Co) are calculated for their ferromagnetic phase in the crystal structure, using density-functional band-structure theory. Large polar Kerr effects are predicted for several of these compounds, with - for a reasonable spectral broadening of 0.4 eV - maximum Kerr rotations of for and , for and , respectively. The Kerr spectra of , and with (001) magnetization are found to be very similar in shape, as are also those of and . The origin of the large Kerr effect in the alloys is shown to be caused by the spin - orbit coupling strength of Pt. A magnetic moment of moderate size on the 3d atom suffices in these materials to already create an appreciable Kerr effect. The influence of the optical transition matrix elements, magnetic moments and spin - orbit coupling strength on each of the constituent atoms are furthermore analysed. The orientation dependence of the polar Kerr spectra of some of the compounds are investigated by calculating in addition the polar Kerr spectra of some compounds for the (111) magnetization axis. The Kerr spectra of the (111) magnetization are found to be practically identical to that of the (001) magnetization.

First‐principles study of the giant magneto‐optical Kerr effect in MnBi and related compounds

First‐principles band‐structure calculations of the magneto‐optical Kerr spectra of MnBi and related compounds are reported. We find that band‐structure theory, based on density‐functional theory in the local spin‐density approximation, explains the measured Kerr effect of MnBi very well. A giant Kerr rotation of about −1.75° at 1.8 eV photon energy is given by our ab initio calculations, in accordance with recent experiments. A second peak at 3.4 eV in the Kerr rotation spectrum, however, comes out smaller in our calculations than what was recently measured. It is discussed that this can be due to the Mn–Bi stoichiometry. The microscopic origin of the giant Kerr effect in MnBi is analyzed in detail. We find that the huge Kerr effect in MnBi is caused by the combination of a sizeable magnetic moment of 3.7 μB on manganese, the large spin‐orbit coupling of bismuth, and a strong hybridization between the manganese d bands and the bismuth p states. The magneto‐optically active states are mainly the p states ...

Calculation of the magneto-optical properties of ferromagnetic metals using the spin-polarized relativistic LMTO method☆

Abstract An efficient method of self-consistent spin-polarized relativistic calculations and an original technique of calculation of the conductivity tensor have been developed. The method has been applied to ferromagnetic Fe, Co, Ni and Pu. Spin and orbital magnetic moments and the Kerr rotation angle have been evaluated.

Theory of the giant magneto-optical Kerr effect in MnPt3 and PtMnSb

Abstract The magueto-optical (MO) Kerr effect in the manganese-platinum compounds MnPt 3 and PtMnSb is studied from first principles, using density-functional band-structure theory. The calculated Kerr spectra give a good description of the huge Kerr rotations found experimentally in these compounds. The origin of the Kerr rotation is discussed in relationship to the band structure and the spin-orbit (SO) interaction strength of Pt.

Experimental and ab initio theoretical study of optical and magneto-optical properties of Co/Cu multilayers

The polar Kerr rotation and ellipticity spectra were measured in the spectral range 0.8 - 5.5 eV for a set of Co/Cu multilayered structures (MLS). The magneto-optical (MO) response of Co/Cu MLS being related to the -part of the optical conductivity tensor was obtained from the Kerr spectra and tensor component , determined by spectroscopic ellipsometry. The self-consistent spin-polarized fully relativistic linear muffin-tin orbital method within the local spin-density approximation was used to calculate the electronic structure, optical, and MO properties of some model Co/Cu MLS. Good agreement between the measured and calculated optical and MO spectra is observed. The role of the spin - orbit coupling and exchange splitting at the Co and Cu sites, and the hybridization effects are examined and discussed. The spin-polarized Cu interface states appear to give a weak contribution to the - and Kerr spectra whereas the latter ones are strongly influenced by the Cu-dominated optical spectra structure. The results obtained demonstrate that the MO properties of real large-period multilayered structures can be quantitatively predicted from first-principles band-structure calculations.

Fermi surface, bonding, and pseudogap in MoSi2

Abstract The electronic structure and Fermi surface of molybdenum disilicide has been calculated using local-density functional theory (LDA) and the linear muffin-tin orbital method (LMTO). The energy bands are analyzed in detail for their orbital character. Our explanation for the presence of a pseudogap after the seventh band is that the two Si s bands lie low and that there are five Mo d-Si p pair bands. The configuration is approximately Mo 4d5 Si2 3s2 3p2.5. An explanation in terms of directed bond-orbitals was not achieved. The calculated angular dependence of the extremal Fermi surface cross-section areas are in good qualitative agreement with de Haas-van Alphen (dHvA) measurements. However, in order to obtain quantitative agreement, the Mo dx2−y2 orbital energy has to be shifted upwards by 0.41 eV and the Mo dxy energy downwards by 0.20 eV. This deficiency is ascribed to the use of a local exchange-correlation potential.

Magneto-optical spectroscopy of d- and f-ferromagnetic materials: recent theoretical progress (Review Article)

The current status of theoretical understanding of the optical and magneto-optical (MO) spectra of 3d, 4f and 5f compounds is reviewed. Energy band theory based upon the local spin-density approximation (LSDA) describes the optical and MO spectra of transition metal compounds reasonably well. Examples which we examine in detail are XPt3 compounds (with X=3d V, Cr, Mn, Fe, and Co) in the AuCu3 structure, ternary Heusler alloys NiMnSb, PdMnSb, PtMnSb, and MnBi compound. The LSDA, which is capable of describing the spectra of transition-metal alloys with high accuracy, does not suffice for lanthanide compounds having a correlated 4f shell. A satisfactory description of the optical spectra could be obtained by using a generalization of the LSDA, in which explicitly f electron Coulomb correlations are taken into account (LSDA+U approach). As examples of this group we consider CeSb and CeBi. For CeSb a record Kerr angle of 90° was very recently reported, 90° is the absolute maximum value that can be measured. I...

Optical and magneto-optical spectroscopy of uranium and plutonium compounds: recent theoretical progress

Abstract First-principles calculations are reported which illustrate that, for those actinide compounds where the 5f electrons are sufficiently delocalized, energy band theory based upon the local spin-density approximation (LSDA) describes the optical and MO spectra reasonably well. Examples which we examine in detail are URhAl and UFe2. The delocalized LSDA approach meets limitations for those actinide compounds, where the electrons in the correlated 5f shell are nearly localized. Just as in the case of lanthanide compounds having localized 4f electrons, a satisfactory description of the optical spectra could be obtained by using a generalization of the LSDA, in which explicitly f electron Coulomb correlations are taken into account (LSDA+U approach). A third group consists of compounds in which the 5f electrons are neither fully delocalized nor localized, but have experimentally been classified as quasilocalized. The suitable theoretical approach to such compounds is yet to be resolved. We further consider the Pu monochalcogenides, the unusual physical properties of which were previously treated with different models, and discuss the optical spectrum of PuTe.

Theory of the optical and magneto-optical spectra of cerium and uranium compounds

Abstract The optical and magneto-optical (MO) spectra of cerium and uranium compounds are investigated theoretically, using an energy-band approach in combination with the linear-response formalism. The energy bands are obtained within the local-density approximation (LDA), as well as with its generalization in which explicit on-site Coulomb correlations are included (LDA+U). We find that for CeSb, CeSe, and CeTe the LDA+U approach gives an adequate description of the measured MO spectra. For CeSb we calculate a colossal MO Kerr rotation of about 60°, which is in agreement with recent experiments. For the uranium compounds we find that the LDA gives a good description of the MO spectra, if the 5f-electrons are sufficiently delocalized, as is illustrated by e.g., UAsSe. The MO spectra of the uranium monochalcogenides US, USe, and UTe pose a challenge to present-day correlated band theory: it is shown that for UTe, where the 5f-electrons are quasilocalized, the LDA+U approach gives a reasonable result. For US, and also for USe, a better description is obtained if, as a correction beyond the on-site Coulomb interaction U, a screened hole in the 5f-shell is taken into account.

Magnetooptical spectroscopy of magnetic multilayers: Theory and experiment (A review)

Experimental and theoretical results on the optical and magnetooptical (MO) spectral properties of a series of Co/Cu, Co/Pd, Co/Pt and Fe/Au multilayers are reviewed. Diagonal and off-diagonal components of the optical conductivity tensor have been determined in the photon energy range 0.8-5.5 eV from the polar and longitudinal Kerr rotation as well as ellipticity and ellipsometry measurements. The conductivity tensor has been evaluated on the basis of self-consistent spin-polarized relativistic linear muffin-tin orbital (LMTO) band-structure calculations within the local spin-density approximation. The role of the spin polarization and the spin–orbit interaction in the formation of the magnetooptical Kerr effect (MOKE) spectra as inferred from first-principles calculations is examined and discussed. The high sensitivity of the MO properties to the interface structure is studied by ab initio modeling of the effects of the interfacial alloying, substitutional disorder, and the roughness at the interfaces. ...