TY - JOUR
T1 - Universality of anharmonic motion of heavy rare-earth atoms in hexaborides
AU - Iwasa, Kazuaki
AU - Iga, Fumitoshi
AU - Yonemoto, Ari
AU - Otomo, Yuka
AU - Tsutsui, Satoshi
AU - Baron, Alfred Q.R.
N1 - Publisher Copyright:
© 2014 The Physical Society of Japan.
PY - 2014/9/15
Y1 - 2014/9/15
N2 - Phonons of TbB6 are studied by inelastic X-ray scattering and compared with those of GdB6 and DyB6. Measured low-lying phonon modes located near 6 meV soften distinctly with decreasing temperature, particularly the longitudinal phonon that is dominated by the motion of Tb ions at q1 =( 1/2; 0; 0). The magnitude and temperature dependence of phonon energy are between those of GdB6 and DyB6. We derive a Landau-type free-energy expansion with respect to the atomic displacement in TbB6, and discuss a general feature among these three compounds. The systematic variation in the phonon characteristics of these hexaborides and the first-order-like instability indicate the universality of the anharmonic motion of heavy rare-earth atoms in RB6 (R = Gd, Tb, and Dy).
AB - Phonons of TbB6 are studied by inelastic X-ray scattering and compared with those of GdB6 and DyB6. Measured low-lying phonon modes located near 6 meV soften distinctly with decreasing temperature, particularly the longitudinal phonon that is dominated by the motion of Tb ions at q1 =( 1/2; 0; 0). The magnitude and temperature dependence of phonon energy are between those of GdB6 and DyB6. We derive a Landau-type free-energy expansion with respect to the atomic displacement in TbB6, and discuss a general feature among these three compounds. The systematic variation in the phonon characteristics of these hexaborides and the first-order-like instability indicate the universality of the anharmonic motion of heavy rare-earth atoms in RB6 (R = Gd, Tb, and Dy).
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U2 - 10.7566/JPSJ.83.094604
DO - 10.7566/JPSJ.83.094604
M3 - Article
AN - SCOPUS:84925003633
VL - 83
JO - Journal of the Physical Society of Japan
JF - Journal of the Physical Society of Japan
SN - 0031-9015
IS - 9
M1 - 094604
ER -