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arXiv · 2201.06194

Elastic Soft Mode and Electric Quadrupole Response in Excitonic Insulator Candidate (Ta$_{0.952}$V$_{0.048}$)$_2$NiSe$_5$: Contribution of Electron-Phonon Interaction

Ryosuke Kurihara·Yusuke Hirose·Sumika Sano·Keisuke Mitsumoto·Atsushi Miyake·Masashi Tokunaga·Rikio Settai
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Abstract

We performed ultrasonic measurements on (Ta$_{0.952}$V$_{0.048}$)$_2$NiSe$_5$ to investigate the contribution of acoustic phonons at the zone center to structural and possible excitonic transitions. The transverse elastic constant $C_{55}$ with irreducible representation $B_\mathrm{2g}$ exhibits softening over 90\% above a transition temperature of $T_\mathrm{s} = 280$ K, indicating the soft mode of corresponding TA phonons. Our analysis based on the quadrupole response indicates that the electron-phonon interaction contributes to the excitonic transition in addition to the hybridization between the conduction and valence bands if the excitonic transition is realized.

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Ryosuke Kurihara, Yusuke Hirose, Sumika Sano, Keisuke Mitsumoto, Atsushi Miyake, Masashi Tokunaga, Rikio Settai. 2022-01-17. Elastic Soft Mode and Electric Quadrupole Response in Excitonic Insulator Candidate (Ta$_{0.952}$V$_{0.048}$)$_2$NiSe$_5$: Contribution of Electron-Phonon Interaction. https://doi.org/10.7566/jpsj.91.024601

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