Low-energy excitation spectra in the excitonic phase of cobalt oxides

Tomoki Yamaguchi, Koudai Sugimoto, Yukinori Ohta

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16 Citations (Scopus)


We study the excitonic phase and low-energy excitation spectra of perovskite cobalt oxides. Constructing the fiveorbital Hubbard model defined on the three-dimensional cubic lattice for the 3d bands of Pr0.5Ca0.5CoO3, we calculate the excitonic susceptibility in the normal state in the random-phase approximation (RPA) to show the presence of the instability toward excitonic condensation. On the basis of the excitonic ground state with a magnetic multipole obtained in the mean-field approximation, we calculate the dynamical susceptibility of the excitonic phase in the RPA and find that there appear a gapless collective excitation in the spin-transverse mode (Goldstone mode) and a gapful collective excitation in the spin-longitudinal mode (Higgs mode). The experimental relevance of our results is discussed.

Original languageEnglish
Article number043701
JournalJournal of the Physical Society of Japan
Issue number4
Publication statusPublished - 2017 Apr 15
Externally publishedYes

ASJC Scopus subject areas

  • General Physics and Astronomy


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