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| 2. |
- Boukhvalov, D. W., et al.
(författare)
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Electronic structure of a Mn-12 molecular magnet : Theory and experiment
- 2007
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 75:1, s. 014419-
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Tidskriftsartikel (refereegranskat)abstract
- We used site-selective and element-specific resonant inelastic x-ray scattering (RIXS) to study the electronic structure and the electron interaction effects in the molecular magnet [Mn12O12(CH3COO)(16)(H2O)(4)]center dot 2CH(3)COOH center dot 4H(2)O, and compared the experimental data with the results of local spin density approximation +U electron structure calculations which include the on-site Coulomb interactions. We found a good agreement between theory and experiment for the Coulomb repulsion parameter U = 4 eV. In particular, the p-d band separation of 1.8 eV has been found from the RIXS spectra, which is in accordance with the calculations. Similarly, the positions of the peaks in the XPS spectra agree with the calculated densities of p and d states. Using the results of the electronic structure calculations, we determined the intramolecular exchange parameters, and used them for diagonalization of the Mn-12 spin Hamiltonian. The calculated exchanges gave the correct ground state with the total spin S = 10.
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| 3. |
- Boukhvalov D. W., Kurmaev E. Z. , Moewes A. , Zatsepin D. A., Cherkashenko V. M., Nemnonov S. N., Finkelstein L. D. , Yarmoshenko Yu. M., Neumann M., Dobrovitski V. V. , Katsnelson M. I. , Lichtenstein A. I. , Harmon B. N. , Kögerler P.
(författare)
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Electronic structure of magnetic molecules V15: LSDA+U calculations, X-ray emission and photoelectron spectra
- 2003
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Ingår i: Physical Review B. ; 67, s. 134408-
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Tidskriftsartikel (refereegranskat)
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| 4. |
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| 6. |
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| 7. |
- Galakhov, V. R., et al.
(författare)
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Electronic structure and x-ray spectra of defective oxides LixCoO2
- 2006
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 74:4, s. 045120-
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Tidskriftsartikel (refereegranskat)abstract
- X-ray absorption, resonant x-ray emission, and x-ray photoelectron spectra of the valence band and core levels have been measured for LixCoO2 (0.6 <= x <= 1.0). Resonant O K alpha x-ray emission spectra of LiCoO2 showed localized excitonic states due to a dd transition between unoccupied and occupied Co 3d states. On the basis of measurements of Co 3s x-ray photoelectron and Co 2p and O 1s x-ray absorption spectra it was established that in defective cobaltites the electronic holes are localized mainly in O 2p states. Evidence of phase separation in LixCoO2 has been found.
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| 8. |
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| 9. |
- Kurmaev, E. Z., et al.
(författare)
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Spectroscopic observation of polaron-lattice band structure in the conducting polymer polyaniline
- 2001
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Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 13:17, s. 3907-3912
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Tidskriftsartikel (refereegranskat)abstract
- We present the results of soft x-ray emission measurements for undoped and protonated polyemeraldine. We show that the polaron-lattice band structure fully accounts for the observed x-ray transitions. A finite spectral intensity of C Kα and N Kα XES is observed at the Fermi level for protonated polyemeraldine, supporting the applicability of the polaronic-metal model for highly conducting polymers.
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| 10. |
- Magnuson, Martin, 1965-, et al.
(författare)
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Magnetic circular dichroism in X-ray fluorescence of Heuseler alloys at threshold excitation
- 2001
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Ingår i: Solid State Communications. - 0038-1098 .- 1879-2766. ; 117:2, s. 79-82
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Tidskriftsartikel (refereegranskat)abstract
- The results of fluorescence measurements of magnetic circular dichroism (MCD) in Mn L2,3 X-ray emission and absorption for Heusler alloys NiMnSb and Co2MnSb are presented. Very intense resonance Mn L3 emission is found at the Mn 2p3/2 threshold and attributed to a peculiarity of the threshold excitation in materials with a half-metallic character of the electronic structure. The excitation energy dependence of Mn L2,3 X-ray emission spectra (XES) was measured at beamline ID12B at the European Synchrotron Radiation Facility (ESRF, Grenoble) using 83% circularly polarized X-rays. A very large MCD effect found in XES is attributed to strong exchange splitting of spin-up and spin-down Mn 3d states. The anomalously high ratio of L2 emission intensity to L3 emission intensity is found.
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| 11. |
- Magnuson, Martin, et al.
(författare)
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Resonant L_alpha,betha X-ray emission and L2,3 X-ray absorption spectra of 3d metals in Co2MnZ (Z=Al,Ga,Sn,Sb) Heusler alloys as an element-selectve probe of spin character of valence band
- 2005
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 144-147, s. 765-769
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Tidskriftsartikel (refereegranskat)abstract
- The 3d metal resonant X-ray emission spectra (RXES) and L3,2 X-ray absorption spectra (XAS) of the Co2MnZ (Z=Al, Ga, Sn, Sb) alloys were measured using linearly polarized soft X-rays. The Mn and Co spectra are compared with results of spin-polarized calculations of Mn 3d and Co 3d partial densities of states performed for each alloy. It is found that a satellite observed at the high-energy side of Mn spectra is due to the localized Mn 3d states located above the Fermi energy. It is shown that the presence of the same satellite structure indicates a higher degree of spin-polarization of Mn 3d states than Co 3d states.Both the intensity of the satellite structure in Mn spectra and the /, peak ratio are increased and follow the atomic number of Z element. The effect is especially strong when excitating slightly above the L3 and L2 threshold energies as well as at resonance. We observe a correlation between these spectral parameters and the magnitude of local magnetic moment. The changes occurring in the Mn RXES are in good agreement with a predicted decrease in p–d hybridization (between the atoms of Z element and Mn atoms). The calculated local density of Mn 3d states at the Fermi energy follows the same trend as the hybridization. This suggests that RXES of 3d metals can be used to monitor the degree of spin-polarization of the valence band states and the local density of states at the Fermi level. Note that neither the Mn L2,3 absorption nor the Co L2,3 and Co emission spectra of the alloys are affected by the different composition (different Z elements).
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| 12. |
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| 13. |
- Yablonskikh, M. V., et al.
(författare)
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On the bonding situation in TlCo2Se2
- 2006
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Ingår i: Journal of Physics: Condensed Matter. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 18, s. 1757-1768
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of TlCo2Se2 has been investigated by means of band structure calculations and x-ray photoelectron and emission spectroscopy (XPS and XES). The formation of the valence band is described in connection with calculations of partial densities of states of the valence band and Co Lα,β x-ray emission () aligned to the binding energy scale. The experimental results are in agreement with the calculated distribution of Co 3d states, which lie close to the Fermi level. The effect of Co–Se bonding is seen as satellite structures in the XPS Co 2p signals. Thermoelectric and Hall effect data as well as resistivity measurements show that TlCo2Se2 is metallic with electron holes as charge carriers with broadband mobility characteristics. The observed anisotropy of the resistivity in the ab plane and along c remains constant as a function of temperature, i.e. without signs of the magnetic ordering that occurs (TN~85 K). The results of local spin density functional calculations show ferromagnetic coupling within the cobalt plane as a result of direct magnetic interactions between the magnetic moments.
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| 14. |
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| 15. |
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| 16. |
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| 17. |
- Zatsepin, D.A., et al.
(författare)
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Valence states of copper ions and electronic structure of LiCu2O2
- 1998
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Ingår i: Phys Rev B. ; 57:8, s. 4377-4381
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of LiCu2O2 was studied using x-ray emission and photoelectron spectroscopy (valence band and core levels) as well as band-structure calculations in terms of LSDA and LSDA+U approaches. According to the x-ray emission and photoelectron spectra the valence states of the Cu atoms are found to be mixed, i.e. 2+ and 1+.
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