Universität Osnabrück, Graduiertenkolleg Mikrostruktur oxidischer

GRADUIERTENKOLLEG MIKROSTRUKTUR OXIDISCHER KRISTALLE 23
V3O5 at room temperature (possible oxidation effect occurred at the surface). For V6O13, a very small shift of
the 3d band maximum is observed. Using UPS a shift of about 0.15 eV to smaller binding energies in the insulating
phase of this system was reported [17]. Clear changes are observed in the V4O7 VB spectra through the
MIT. The V 3d peak becomes wider in the metallic phase. A finite spectral weight at the Fermi level at room
temperature is observed, consistent with its metallic behavior. For all investigated vanadium oxides, strong hybridization
of the V 3d and O 2p states in the valence band was found.
Ausblick
We have recently started the XPS investigation of La1-xBaxMn1-y(Co, Ni)yO3 single crystals. Further investigation
of these materials by other spectroscopic techniques (XES) is desirable. Additional XPS measurements of
Fe1-xCuxCr2S4 in the intermediate doping regime are necessary in order to answer the longstanding question
about the Cu valence state in these compounds [10,11]. For this good quality single crystals are required.
Literatur
[1] A. P. Ramirez, J. Phys.: Condens. Matter 39, 8171-8199, 1997 (and the references therein)
[2] A. P. Ramirez, R. J. Cava and J. Krajewski, Nature 386, 156-159, 1997
[3] Y. Moritomo, A. Asamitsu, H. Kuwahara and Y. Tokura, Nature 380, 141-144, 1996
[4] P. D. Battle, S. J. Blundell, M. A. Green, W. Hayes, M. Honold, A. K. Klehe, N. S. Laskey, J. E. Millburn,
L. Murphy, M. J. Rosseinsky, N. A. Samarin, J. Singleton, N. E. Sluchanko, S. P. Sullivan and J. F. Vente, J.
Phys.: Condens. Matter 8, L427-434, 1996
[5] Y. Shimakawa, Y. Kubo and T. Manako, Nature 379, 53—55, 1996
[6] J. Y. Chan, S. M. Kauzlarich, P. Klavins, R. N. Shelton and D. J. Webb, Phys. Rev. B 57, R 8103-8106,
1998
[7] C. Zener, Phys. Rev. 82, 403, 1951
[8] A. J. Millis, P. B. Littlewood and B. I. Shraiman, Phys. Rev. Lett. 74, 5144-5147, 1995
[9] Y. Tokura and Y. Tomioka, J. Magn. Magn. Mat. 200, 1-23, 1999
[10] F. K. Lotgering and R. P. van Stapele, Sol. St. Commun. 5, 143-146, 1967
[11] J. B. Goodenough, J. Phys. Chem. Sol. 30, 261-280, 1969
[12] M. Imada, A. Fujimori and Y. Tokura, Rev. Mod. Phys. 70, 1030-1263, 1998 (and the references therein)
[13] T. M. Rice and H. Launois and J. P. Pouget, Phys. Rev. Lett. 73, 3042, 1994
[14] R. M. Wentzcovitch, W. W. Schultz and P. Allen, Phys. Rev. Lett. 72, 3389, 1994
[15] S. Satpathy, Z. S. Popovic and F. R. Vukajlovic, Phys. Rev. Lett. 76, 960-963, 1996
[16] J. H. van Vleck, Phys. Rev. 45, 405, 1934
[17] S. Shin, S. Suga, M. Taniguchi, M. Fujisawa, H. Kanzaki, A. Fujimori, H. Daimon, Y. Ueda, K. Kosuge
and S. Kachi, Phys. Rev. B 41, 4993-5009, 1990
Eigene Publikationen
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M. Demeter , St. Bartkowski, E. Z. Kurmaev , M. Neumann , V. M. Cherkashenko , V. L. Volkov and G.
C. Zakharova, Investigation of the mixed-valent system V2-xMoxO5 by XPS, SPIE 3724, 296-300 (1999)
2
M. Coldea, M. Neumann, D. Todoran, M. Demeter, R. Tetean, V. Pop, X-ray Photoelectron Spectroscopy
and Magnetism of GdNi5-xAlx, Studia Univ. Babes-Bolyai, Ser. Physika XLIV 2, 35 (1999)
3
M. Demeter, M. Neumann and W. Reichelt, Mixed-valence vanadium oxides studied by XPS, Surf.Sci. 454-
456, 41, (2000)
4
V. Tsurkan, D. Samusi, E. Burzo, V. Pop, M. Neumann, M. Demeter, M. Baran, R. Szymczak and H.
Szymczak, Magnetic properties of FeCr2S4:Cu,In semiconductors-Interface Controlled Materials 12, 5897-
5904, 2000
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V. Tsurkan, M. Demeter, B. Schneider, D. Hartmann and M. Neumann, Exchange splitting of the Cr, Fe
and Mn 3s XPS spectra in some ternary magnetic semiconductor sulphides, Solid St. Commun. 114, 149,
(2000)
6
V. Tsurkan, St. Plogmann, M. Demeter, D. Hartmann and M. Neumann, Splitting of the Cr 2p ions states in
some ternary sulphides and selenides, Eur. Phys. J. B 15, 401, (2000)
7
E. Z. Kurmaev, A. V. Postnikov, H. M. Palmer, C. Greaves, St. Bartkowski, V. Tsurkan, M. Demeter, D.
Hartmann, M. Neumann, D. A Zatsepin, V. R. Galakhov, S. N. Shamin and V. Trofimova, Electronic structure
of FeCr2S4 and Fe0.5Cu0.5Cr2S4, J. Phys.: Condens. Matter 12, 5411, (2000)
8
V. R. Galakhov, L. D. Finkelstein, D. A. Zatsepin, A. A.Samokhvalov, S. V. Naumov, E. Z. Kurmaev, M.
Demeter, St. Bartkowski, M. Neumann and A. Moewes, Cu 3d impurity states in Mg1-xCuxO -solid solutions:
X- ray photoelectron and X- ray emission study, Phys. Rev. B 62, 4922-4926 (2000)