Pressure-induced phonon softenings and the structural and magnetic transitions in CrO 2

Sooran Kim, Kyoo Kim, Chang Jong Kang, B. I. Min

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18 Scopus citations

Abstract

To investigate the pressure-induced structural transitions of chromium dioxide (CrO 2), phonon dispersions and total-energy band structures are calculated as a function of pressure. The observed structural transition has been theoretically reproduced at P 10 GPa from the ground-state tetragonal CrO 2 (t-CrO 2) of the rutile type to orthorhombic CrO 2 (o-CrO 2) of the CaCl 2 type. The half-metallic property is found to be preserved in o-CrO 2. The softening of the Raman-active B 1g phonon mode, which is responsible for this structural transition, is demonstrated. The second structural transition is found to occur for P≥61.1 GPa from ferromagnetic (FM) o-CrO 2 to nonmagnetic monoclinic CrO 2 (m-CrO 2) of the MoO 2 type, which is related to the softening mode at q=R(12,0,12). The third structural transition has been identified at P=88.8 GPa from m-CrO 2 to cubic CrO 2 of the CaF 2 type that is a FM insulator.

Original languageEnglish
Article number094106
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume85
Issue number9
DOIs
StatePublished - 19 Mar 2012

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