Berlin 2015 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 100: Correlated Electrons: Other Materials

TT 100.11: Vortrag

Donnerstag, 19. März 2015, 17:45–18:00, H 3005

Correlation driven charge and spin fluctuations in LaCoO₃ — •Michael Karolak¹, Manuel Izquierdo^2,3,6, Serguei L. Molodtsov^2,4,5, and Alexander I. Lichtenstein⁶ — ¹Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Am Hubland, 97074 Würzburg — ²European XFEL GmbH, Albert-Einstein-Ring 19, 22761 Hamburg, Germany — ³Synchrotron Soleil, L’Orme des Merisiers St-Aubin, BP-48, 91192, Gif-sur-Yvette, France — ⁴Institute of Experimental Physics, Technische Universität Bergakademie Freiberg, 09599 Freiberg, Germany — ⁵ITMO University, Kronverkskiy pr. 49, 197101 St. Petersburg, Russia — ⁶Institut für Theoretische Physik, Universität Hamburg, Jungiusstraße 9, 20355 Hamburg, Germany

The spin transition in LaCoO₃ has been investigated within the DFT+DMFT formalism using continuous time quantum Monte Carlo. Calculations on the experimental rhombohedral atomic structure with two Co sites per unit cell show that an independent treatment of the Co atoms results in a ground state with charge imbalance induced by electronic correlations. Each atom shows a contribution from either a d⁵ or a d⁷ state in addition to the main d⁶ state. These charged states play a relevant role in the spin transition which can be understood as a low spin-high spin (LS-HS) transition with significant contributions (∼ 10%) to the LS and HS states of d⁵ and d⁷ states. A thermodynamic analysis reveals that the introduction of charge imbalance significantly lowers the total energy of the system.