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 - http://www.scopus.com/inward/record.url?scp=84859042131&partnerID=8YFLogxK
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 -