Repozytorium Uniwersytetu Jagiellońskiego

Defect states and excitations in a Mott insulator with orbital degreesof freedom : Mott-Hubbard gap versus optical and transport gaps in doped systems

Defect states and excitations in a Mott insulator ...

Metadane (Dublin Core) Avella, Adolfo pl Horsch, Peter pl Oleś, Andrzej [SAP11009398] pl 2015-05-27T12:33:08Z 2015-05-27T12:33:08Z 2013 pl
dc.identifier.issn 1098-0121 pl
dc.language eng pl
dc.rights Dodaję tylko opis bibliograficzny *
dc.rights.uri *
dc.title Defect states and excitations in a Mott insulator with orbital degreesof freedom : Mott-Hubbard gap versus optical and transport gaps in doped systems pl
dc.type JournalArticle pl
dc.abstract.en We address the role played by charged defects in doped Mott insulators with active orbital degrees of freedom. It is observed that defects feature a rather complex and rich physics, which is well captured by a degenerate Hubbard model extended by terms that describe crystal-field splittings and orbital-lattice coupling, as well as by terms generated by defects such as the Coulomb potential terms that act both on doped holes and on electrons within occupied orbitals at undoped sites. We show that the multiplet structure of the excited states generated in such systems by strong electron interactions is well described within the unrestricted Hartree-Fock approximation, once the symmetry breaking caused by the onset of magnetic and orbital order is taken into account. Furthermore, we uncover spectral features that arise within the Mott-Hubbard gap and in the multiplet spectrum at high energies due to the presence of defect states and strong correlations. These features reflect the action on electrons/holes of the generalized defect potential that affects charge and orbital degrees of freedom, and indirectly also spin ones. This study elucidates the mechanism behind the Coulomb gap appearing in the band of defect states and investigates the dependence on the electron-electron interactions and the screening by the orbital-polarization field. As an illustrative example of our general approach, we present explicit calculations for the model describing three t_{2g} orbital flavors in the perovskite vanadates doped by divalent Sr or Ca ions, such as in La_{1-x}Sr_{x}VO_{3} and Y_{1-x}Ca_{x}VO_{3} systems. We analyze the orbital densities at vanadium ions in the vicinity of defects and the excited defect states which determine the optical and transport gaps in doped systems. pl
dc.description.volume 87 pl
dc.description.number 4 pl
dc.description.publication 2 pl
dc.identifier.doi 10.1103/PhysRevB.87.045132 pl
dc.identifier.eissn 1550-235X pl
dc.identifier.eissn 1538-4489 pl
dc.title.journal Physical Review. B, Condensed Matter and Materials Physics pl
dc.language.container eng pl
dc.affiliation Wydział Fizyki, Astronomii i Informatyki Stosowanej : Instytut Fizyki im. Mariana Smoluchowskiego pl
dc.subtype Article pl
dc.identifier.articleid 045132 pl
dc.rights.original bez licencji pl
.pointsMNiSW [2013 A]: 35

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