The electronic, magnetic and orbital structures of KCrF3 are determined in all its recently identified crystallographic phases (cubic, tetragonal, and monoclinic) with a set of ab initio local spin density approximation (LSDA) and LSDA+U calculations. The high-temperature undistorted cubic phase appears as a metal from LSDA, but it is a Mott insulator with a gap of 1.72 eV at the LSDA+U level. The tetragonal and monoclinic phases of KCrF3 exhibit cooperative Jahn-Teller distortions concomitant with staggered 3x2−r2/3y2−r2 orbital order. We find that the energy gains due to the Jahn-Teller distortion are 82 and 104 meV per chromium ion in the tetragonal and monoclinic phases, respectively. These phases show A-type magnetic ordering and have a band gap of 2.48 eV. In this Mott insulating state, KCrF3 has a substantial conduction bandwidth leading to the possibility for the kinetic energy of charge carriers in electron- or hole-doped derivatives of KCrF3 to overcome the polaron localization at low temperatures, in analogy with the situation encountered in the colossal magnetoresistive manganites.
|Number of pages||7|
|Journal||Physical review B: Condensed matter and materials physics|
|Publication status||Published - 2008|