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

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

doi:10.1103/PhysRevB.85.094106

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

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

Pohang University of Science and Technology

Research output: Contribution to journal › Article › peer-review

22 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 language	English
Article number	094106
Journal	Physical Review B - Condensed Matter and Materials Physics
Volume	85
Issue number	9
DOIs	https://doi.org/10.1103/PhysRevB.85.094106
State	Published - 19 Mar 2012

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10.1103/PhysRevB.85.094106

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@article{43edd5556b1c49d28895c69c3b203001,

title = "Pressure-induced phonon softenings and the structural and magnetic transitions in CrO 2 ",

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.",

author = "Sooran Kim and Kyoo Kim and Kang, \{Chang Jong\} and Min, \{B. I.\}",

year = "2012",

month = mar,

day = "19",

doi = "10.1103/PhysRevB.85.094106",

language = "English",

volume = "85",

journal = "Physical Review B - Condensed Matter and Materials Physics",

issn = "1098-0121",

publisher = "American Physical Society",

number = "9",

}

TY - JOUR

T1 - Pressure-induced phonon softenings and the structural and magnetic transitions in CrO 2

AU - Kim, Sooran

AU - Kim, Kyoo

AU - Kang, Chang Jong

AU - Min, B. I.

PY - 2012/3/19

Y1 - 2012/3/19

N2 - 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.

AB - 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.

UR - https://www.scopus.com/pages/publications/84859042131

U2 - 10.1103/PhysRevB.85.094106

DO - 10.1103/PhysRevB.85.094106

M3 - Article

AN - SCOPUS:84859042131

SN - 1098-0121

VL - 85

JO - Physical Review B - Condensed Matter and Materials Physics

JF - Physical Review B - Condensed Matter and Materials Physics

IS - 9

M1 - 094106

ER -

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

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