Strong spin-phonon coupling unveiled by coherent phonon oscillations in Ca2RuO4

Min Cheol Lee, Choong H. Kim, Inho Kwak, C. W. Seo, Changhee Sohn, F. Nakamura, C. Sow, Y. Maeno, E. A. Kim, T. W. Noh, K. W. Kim

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19 Scopus citations

Abstract

We utilize near-infrared femtosecond pulses to investigate coherent phonon oscillations of Ca2RuO4. The coherent Ag phonon mode of the lowest frequency changes abruptly not only its amplitude but also the oscillation phase as the spin order develops. In addition, the phonon mode shows a redshift entering the magnetically ordered state, which indicates a spin-phonon coupling in the system. Density functional theory calculations reveal that the Ag oscillations result in octahedral tilting distortions, which are exactly in sync with the lattice deformation driven by the magnetic ordering. We suggest that the structural distortions by the spin-phonon coupling can induce the unusual oscillation phase shift between impulsive and displacive type oscillations.

Original languageEnglish
Article number144306
JournalPhysical Review B
Volume99
Issue number14
DOIs
StatePublished - 15 Apr 2019

Bibliographical note

Funding Information:
We thank S. B. Chung for fruitful discussions. This work was supported by the Institute for Basic Science (IBS) in Korea (Grant No. IBS-R009-D1). K.W.K. was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (Grants No. NRF-2015R1A2A1A10056200 and No. 2017R1A4A1015564). This work was supported by JSPS KAKENHI (Grants No. JP15H05852, No. JP15K21717, and No. JP17H06136) and JSPS Core-to-Core program. C.S. acknowledges support of the JSPS International Research Fellowship (Grant No. JP17F17027). E.-A.K. acknowledges support from the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Science and Engineering under Grant No. DE-SC0018946 and from a Simons Fellowship in Theoretical Physics, Grant No. 392182.

Publisher Copyright:
© 2019 American Physical Society.

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