S.V. Halilov

Optical Measurements and Band Calculations of FeSi.

Reflectivity measurements of high quality FeSi single crystal have been performed at 6 and 300 K over a very wide spectral region from 0.05 to 30 eV. The optical conductivity is obtained by a Kramers-Kronig transformation, and it is discussed in connection with the recent band calculation in which the relativistic spin-orbit effects are taken into account and with other measurements done on FeSi before. The result of direct photoconductivity measurement in the spectral region from 200 to 800 cm -1 is also presented.

Spin, orbital moments and magneto-optical properties of MPt3 (M = Cr, Mn, Fe, Co) compounds

Abstract We have studied trends in the ab initio electronic structure, spin moments, orbital moments and magneto-optical (MO) properties of MPt 3 compounds. The calculated quantities agree well with the experimental data. It was found that values of the local orbital moments are closely connected with the predominant spin character of electronic states near the Fermi energy ( E F ). Features of the MO spectra of compounds are primarily defined by the absorptive off-diagonal conductivity σ 2, xy ( ω ). The spin decomposition of this quantity showed that at the MO resonance energy σ 2, xy ( ω ) is formed mainly by spin-up electronic transitions to an unoccupied part of the hybridized {M3d ↑-Pt5d ↑} band. These transitions are intense for CrPt 3 and MnPt 3 , having high MO activity. A reduction of the unoccupied part of {M3d ↑-Pt5d ↑} band in FePt 3 and CoPt 3 results in the weak electronic transitions and in small calculated Kerr rotation values for these compounds.

Effects of degeneracy removal on optical and magneto-optical properties of 3d ferromagnetic metals

The authors consider the effects of degeneracy removal due to magnetism and spin-orbit coupling on the optical and magneto-optical properties of Fe, Co and Ni. Both analytical and numerical calculations were carried out in order to investigate the frequency dependence of the conductivity tensor in the presence of spin-polarisation and spin-orbit coupling. Anomalies of the tensor are predicted in the infrared region at energies of the order of the spin-orbit splitting. A universal explanation is proposed for these anomalies. This is that paired singularities of the tensor components, at energies of the order of the d-band give information about the exchange splitting of the d-band. The obtained results are in accordance with optical, magneto-optical and photoemission measurements.

First-order metamagnetic transition in iron monosilicide

The influence of a high magnetic field on the band structure and optical conductivity of FeSi has been studied by the ab initio full-potential LMTO-PW and relativistic LMTO-ASA methods with an applied field included. It is found that the applied external magnetic field induces a metallic magnetic state through a first-order metamagnetic transition, i.e. at a critical magnetic field of about there is a large steplike increase in the calculated magnetization, with a magnetic moment of . The magnetized state persists while the field is gradually reduced from above the metamagnetic transition (a hysteresis effect). The calculated optical conductivity (OC) at the critical field differs substantially from the zero-field OC in the infrared region.

Ab initio calculated magneto-optical spectra of half-metallic ferromagnets

Abstract Within the density-functional theory approach we have carried out fully relativistic calculations of the conductivity tensor, the Kerr rotation and ellipticity for PtMnSb, PdMnSb and NiMnSb compounds. Our calculations successfully reproduced the huge Kerr effect for PtMnSb and give the correct positions of the main features for the other compounds. The origins of the main peculiarities are discussed.

Ab initio calculated magneto-optical spectra of half metallic ferromagnets with C1b structure☆

Abstract Within the density-functional theory approach we have carried out fully relativistic calculations of the conductivity tensor, the Kerr rotation and ellipticity for PtMnSb, PdMnSb and NiMnSb compounds. Our calculations successfully reproduce the huge Kerr effect for PtMnSb and give the correct positions of the main features for other compounds. The origins of the main peculiarities are discussed.

Ab initio studies of optical and magneto-optical spectra in 3d- and 4f-atom-based compounds

Ab initio magneto-optical (MO) calculations were carried out for three groups of the 3d- and 4f-atom-based ferromagnetic compounds. The results obtained show a good agreement with the experimental spectra of the MO Kerr and Faraday effects. To study the mechanism of the MO spectra formation, numerical experiments were conducted and the trends in the MO spectra of the compounds were explained in terms of their electronic structure.

Spin, orbital moments and magneto-optical properties of MPt3 compounds

Abstract We studied trends in ab initio electronic structure, spin moments, orbital moments and magneto-optical (MO) properties of MPt 3 compounds. Calculated quantities agree well with existing experimental data. It was found that values of local orbital moments are closely connected with the predominant spin character of the electronic states near the Fermi energy ( E F ). Features of the MO spectra are primarily defined by the absorptive off-diagonal conductivity σ 2, xy ( ω ).

The investigation of electronic structure in FeSi by optical measurements

Abstract The optical conductivity of FeSi has been obtained by means of a Kramers-Kronig transformation of the reflectivity spectra in the energy region 0.05–32 eV. The result is compared with the optical conductivity obtained by a band calculation, and the electronic structure of FeSi is discussed.