, an orbital-ordered system?T. Saha-Dasgupta1, R. Valentí2, H. Rosner3 and C. Gros4
1 S.N. Bose National Centre for Basic Sciences, JD Block, Sector 3 Salt Lake City, Kolkata 700098, India
2 Institut für Theoretische Physik, Universität Frankfurt - D-60054 Frankfurt, Germany
3 Max-Planck Institute for Chemical Physics of Solids - D-01187 Dresden, Germany
4 Theoretische Physik, Universtät des Saarlandes - D-66041 Saarbrücken, Germany
(Received 2 December 2003; accepted in final form 26 April 2004)
We present first-principles density-functional calculations and downfolding studies of the electronic and magnetic properties of the layered quantum spin system . We discuss explicitly the nature of the exchange paths and the concept of orbital ordering in this material. An analysis of the electronic structure of slightly distorted structures according to various phonon modes allowed in this material suggests that this system may be subject to orbital fluctuations driven by the electron-phonon coupling.
71.20.-b - Electron density of states and band structure of crystalline solids.
71.10.-w - Theories and models of many-electron systems.
71.20.Be - Transition metals and alloys.
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