Electronic structure and magneto-optical Kerr effect of Tm monochalcogenides

Abstract

The optical and magneto-optical ͑MO͒ spectra of Tm monochalcogenides are investigated theoretically from first principles, using the fully relativistic Dirac linear combination of muffin-tin orbitals band structure method. The electronic structure is obtained with the local-spin-density approximation ͑LSDA͒, as well as with the so-called LSDAϩU approach. In contrast to LSDA, where the stable solution in TmTe is a metal, the LSDAϩU gave an insulating ground state. LSDAϩU theory predicts the thulium ion in TmTe to be in an integer divalent state. It also shows a gradual decreasing of the energy gap with reducing of the lattice constant. LSDAϩU theoretical calculations produce a similar energy band structure in TmS and TmSe, with twelve 4 f bands fully occupied and hybridized with chalcogenide p states. The 14th f hole level was found to be completely unoccupied and well above the Fermi level and a hole 13th f level is partly occupied and pinned at the Fermi level. The occupation number of the 13th f level is equal to 0.12 and 0.27 in TmS and TmSe, respectively ͑valence 2.88ϩ and 2.73ϩ͒. Such an energy band structure of thulium monochalcogenides describes well their measured bremsstrahlung isochromat spectroscopy ͑BIS͒, and x-ray and ultraviolet photoemission spectra as well as the optical and MO spectra. The origin of the Kerr rotation realized in the compounds is examined.

Electronic structure and x-ray magnetic circular dichroism in the Heusler alloy Co_{2}FeSi

“…The details of the computational method are described in the previous papers [28][29][30][31], and here we only mention some aspects specific to the present calculations. The calculations were performed for the experimentally observed lattice constant a = 5.658Å [32] as well as for the one theoretically calculated in total energy optimization using the spin-polarized fully relativistic linear-muffin-tinorbital (SPR LMTO) method [33,34] with the combined correction term taken into account.…”

Electronic structure, Fermi surface and dHvA effect in YIn3, LuIn3, and YbIn3

“…It is well known that LDA usually gives a wrong energy position for the 4f states in rare-earth compounds. For nonzero 4f occupation it places the 4f states right at the Fermi level [22,23] in contradiction to various experimental observations. In the case of Gd compounds or divalent Yb 2+ compounds the LDA places the 4f…”

Electronic and magnetic properties of the ferromagnetic superconductor UCoGe

“…It was first pointed out by Gotsis and Strange [56] as well as Brooks and Johansson [57] that XMCD K-spectrum reflects the orbital polarization in differential form / z d l dE 〈 〉 of the p states. It gives a rather simple and straightforward interpretation of the Co XMCD spectrum at the K edge [58].…”