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arXiv · 0707.3565

KCrF_3: Electronic Structure, Magnetic and Orbital Ordering from First Principles

Gianluca Giovannetti·Serena Margadonna·Jeroen van den Brink
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Abstract

The electronic, magnetic and orbital structures of KCrF_3 are determined in all its recently identified crystallographic phases (cubic, tetragonal, and monoclinic) with a set of {\it ab initio} LSDA and LSDA+U calculations. The high-temperature undistorted cubic phase is metallic within the LSDA, but at the LSDA+U level it is a Mott insulator with a gap of 1.72 eV. The tetragonal and monoclinic phases of KCrF_3 exhibit cooperative Jahn-Teller distortions concomitant with staggered 3x^2-r^2/3y^2-r^2 orbital order. We find that the energy gain due to the Jahn-Teller distortion is 82/104 meV per chromium ion in the tetragonal/monoclinic phase, respectively. These phases show A-type magnetic ordering and have a bandgap of 2.48 eV. In this Mott insulating state KCrF_3 has a substantial conduction bandwidth of 2.1 eV, leading to the possibility for the kinetic energy of charge carriers in electron- or hole-doped derivatives of KCrF_3 to overcome the polaron localization at low temperatures, in analogy with the situation encountered in the colossal magnetoresistive manganites.

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Gianluca Giovannetti, Serena Margadonna, Jeroen van den Brink. 2007-07-24. KCrF_3: Electronic Structure, Magnetic and Orbital Ordering from First Principles. https://doi.org/10.1103/physrevb.77.075113

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