Dresden 2014 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 56: Focus Session: Electronic Properties of Spin-Orbit Driven Oxides

TT 56.5: Topical Talk

Mittwoch, 2. April 2014, 11:45–12:15, HSZ 03

Electronic Structure of Honeycomb Iridates and Rhodates from a Density Functional Theory Perspective — •Harald O. Jeschke¹, I. I. Mazin², K. Foyevtsova¹, D. Khomskii³, and Roser Valenti¹ — ¹Institut für Theoretische Physik, Goethe-Universität Frankfurt, Germany — ²Naval Research Laboratory, Washington, USA — ³II. Physikalisches Institut, Universität zu Köln, Germany

Taking a complementary point of view to previous studies that classify the hexagonal iridate Na₂IrO₃ as a realization of the Heisenberg-Kitaev model with dominant spin-orbit coupling, we show that this system represents a highly unusual case in which the electronic structure is dominated by the formation of quasi-molecular orbitals (QMOs), with substantial quenching of the orbital moments [1]. The QMOs consist of six atomic orbitals on an Ir hexagon, but each Ir atom belongs to three different QMOs. We discuss both limiting descriptions for Na₂IrO₃, the itinerant QMO limit valid at small SO coupling and the localized relativistic orbitals limit at large SO coupling and show that the description of Na₂IrO₃ lies in an intermediate regime [2]. We demonstrate that the electronic structure of Na₂IrO₃ is exceptionally sensitive to structural details and analyze role of the various structural distortions. We discuss the application of the QMO picture to Li₂RhO₃ [3].
I. I. Mazin, H. O. Jeschke, K. Foyevtsova, R. Valenti, D. I. Khomskii, Phys. Rev. Lett. 109, 197201 (2012)
K. Foyevtsova, H. O. Jeschke, I. I. Mazin, D. I. Khomskii, R. Valenti, Phys. Rev. B 88, 035107 (2013)
I. I. Mazin et al., Phys. Rev. B 88, 035115 (2013)