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TT: Fachverband Tiefe Temperaturen

TT 24: Correlated Electrons: (General) Theory 2

TT 24.12: Vortrag

Mittwoch, 25. März 2009, 12:45–13:00, HSZ 301

Ab initio correlated electronic structure of Cu oxide and Fe-As compounds: a quantum chemical perspective — •Liviu Hozoi, Mukul Laad, and Peter Fulde — Max-Planck-Institut fuer Physik komplexer Systeme, Dresden

Wavefunction-based methods from modern quantum chemistry are applied to the study of the electronic structure of correlated transition-metal compounds. Whereas the correlation treatment is performed in direct-space, a k-space representation can be obtained later on after accounting for the (strong) short-range correlations. In some cases, a balanced treatment of the short-range interactions, onsite and intersite, is essential for achieving even a qualitatively correct picture.

In cuprates, we find that the Fermi surface (FS) of the hole doped material evolves from small hole pockets in the deeply underdoped region to one with both hole- and electron-like sheets at slightly higher doping and to a large FS consistent with Luttinger's theorem at still higher hole concentrations. Our results offer a route toward a resolution of the controversy generated by the apparent inconsistency between Shubnikov-deHaas measurements and the Luttinger sum rule for underdoped cuprates, as well as with recent Hall-effect data suggesting an electron-like Hall constant for hole doped cuprates at low T.

The multiorbital correlated electronic structure of the recently discovered Fe-As superconducting compounds is also discussed. We compute the ground-state for the undoped case and provide new insight into the nature of doped holes and electrons.