Abnormal phase flip in the coherent phonon oscillations of Ca2RuO4
- 주제(기타) Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter
- 설명문(일반) [Lee, Min-Cheol; Kim, Choong H.; Kwak, Inho; Park, Byung Cheol; Lee, Bumjoo; Noh, T. W.] Inst for Basic Sci Korea, CCES, Seoul 08826, South Korea; [Lee, Min-Cheol; Kim, Choong H.; Kwak, Inho; Park, Byung Cheol; Lee, Bumjoo; Noh, T. W.] Seoul Natl Univ, Dept Phys & Astron, Seoul 08826, South Korea; [Kim, J.; Yoon, S.] Ewha Womans Univ, Dept Phys, Seoul 03760, South Korea; [Kim, J.; Yoon, S.] Ewha Womans Univ, New Renewable Energy Res Ctr NREC, Seoul 03760, South Korea; [Nakamura, F.] Kurume Inst Technol, Dept Educ & Creat Engn, Fukuoka, Fukuoka 8300052, Japan; [Sow, C.; Maeno, Y.] Kyoto Univ, Grad Sch Sci, Dept Phys, Kyoto 6068502, Japan; [Kim, K. W.] Chungbuk Natl Univ, Dept Phys, Cheongju 28644, Chungbuk, South Korea
- 등재 SCIE, SCOPUS
- 발행기관 AMER PHYSICAL SOC
- 발행년도 2018
- URI http://www.dcollection.net/handler/ewha/000000156119
- 본문언어 영어
- Published As http://dx.doi.org/10.1103/PhysRevB.98.161115
초록/요약
We employ an optical pump-probe technique to study coherent phonon oscillations in Ca2RuO4. We find that oscillation amplitude of an A(g) symmetric phonon mode is strongly suppressed at 260 K, a putative transition point of orbital ordering. The oscillation also shows a gradual but huge change in its phase, such that the oscillation even flips over with a 180. change across the temperature. Density functional theory calculations indicate that the Ag phonon has an eigenmode of octahedral distortion with conventional tilting along the a axis and antipolar distortion of apical oxygen. Careful inspection of the lattice captures an unusually large antipolar distortion in low-temperature structures, which may play a crucial role for the phase transition at 260 K.
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