Anomalous infrared spectra of hybridized phonons in type-I clathrate Ba8Ga16Ge30

Kei Iwamoto; Shunsuke Kushibiki; Hironori Honda; Shuhei Kajitani; Tatsuya Mori; Hideki Matsumoto; Naoki Toyota; Koichiro Suekuni; Marcos A. Avila; Toshiro Takabatake

doi:10.7566/JPSJ.82.024601

Anomalous infrared spectra of hybridized phonons in type-I clathrate Ba₈Ga₁₆Ge₃₀

Kei Iwamoto, Shunsuke Kushibiki, Hironori Honda, Shuhei Kajitani, Tatsuya Mori, Hideki Matsumoto, Naoki Toyota, Koichiro Suekuni, Marcos A. Avila, Toshiro Takabatake

Research output: Contribution to journal › Article › peer-review

9 Citations (Scopus)

Abstract

The optical conductivity spectra of the rattling phonons in the clathrate Ba₈Ga₁₆Ge₃₀ are investigated in detail by use of the terahertz time-domain spectroscopy. The experiment has revealed that the lowest-lying vibrational mode of Ba(2)²⁺ ions consist of a sharp Lorentzian peak at 1.2 THz superimposed on a broad tail weighted in the lower frequency regime around 1.0 THz. With decreasing temperature, an unexpected linewidth broadening of the phonon peak is observed, together with monotonic softening of the phonon peak and enhancement of the tail structure. These observed anomalies are discussed in terms of impurity scattering effects on the hybridized phonon system of rattling and acoustic phonons.

Original language	English
Article number	024601
Journal	journal of the physical society of japan
Volume	82
Issue number	2
DOIs	https://doi.org/10.7566/JPSJ.82.024601
Publication status	Published - 2013 Feb
Externally published	Yes

Keywords

Clathrates
Hybridized phonon system
Phonon-impurity interactions
Rattling phonons
THz time-domain spectroscopy

ASJC Scopus subject areas

Physics and Astronomy(all)

Access to Document

10.7566/JPSJ.82.024601

Cite this

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title = "Anomalous infrared spectra of hybridized phonons in type-I clathrate Ba8Ga16Ge30",

abstract = "The optical conductivity spectra of the rattling phonons in the clathrate Ba8Ga16Ge30 are investigated in detail by use of the terahertz time-domain spectroscopy. The experiment has revealed that the lowest-lying vibrational mode of Ba(2)2+ ions consist of a sharp Lorentzian peak at 1.2 THz superimposed on a broad tail weighted in the lower frequency regime around 1.0 THz. With decreasing temperature, an unexpected linewidth broadening of the phonon peak is observed, together with monotonic softening of the phonon peak and enhancement of the tail structure. These observed anomalies are discussed in terms of impurity scattering effects on the hybridized phonon system of rattling and acoustic phonons.",

keywords = "Clathrates, Hybridized phonon system, Phonon-impurity interactions, Rattling phonons, THz time-domain spectroscopy",

author = "Kei Iwamoto and Shunsuke Kushibiki and Hironori Honda and Shuhei Kajitani and Tatsuya Mori and Hideki Matsumoto and Naoki Toyota and Koichiro Suekuni and Avila, {Marcos A.} and Toshiro Takabatake",

year = "2013",

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doi = "10.7566/JPSJ.82.024601",

language = "English",

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publisher = "Physical Society of Japan",

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TY - JOUR

T1 - Anomalous infrared spectra of hybridized phonons in type-I clathrate Ba8Ga16Ge30

AU - Iwamoto, Kei

AU - Kushibiki, Shunsuke

AU - Honda, Hironori

AU - Kajitani, Shuhei

AU - Mori, Tatsuya

AU - Matsumoto, Hideki

AU - Toyota, Naoki

AU - Suekuni, Koichiro

AU - Avila, Marcos A.

AU - Takabatake, Toshiro

PY - 2013/2

Y1 - 2013/2

N2 - The optical conductivity spectra of the rattling phonons in the clathrate Ba8Ga16Ge30 are investigated in detail by use of the terahertz time-domain spectroscopy. The experiment has revealed that the lowest-lying vibrational mode of Ba(2)2+ ions consist of a sharp Lorentzian peak at 1.2 THz superimposed on a broad tail weighted in the lower frequency regime around 1.0 THz. With decreasing temperature, an unexpected linewidth broadening of the phonon peak is observed, together with monotonic softening of the phonon peak and enhancement of the tail structure. These observed anomalies are discussed in terms of impurity scattering effects on the hybridized phonon system of rattling and acoustic phonons.

AB - The optical conductivity spectra of the rattling phonons in the clathrate Ba8Ga16Ge30 are investigated in detail by use of the terahertz time-domain spectroscopy. The experiment has revealed that the lowest-lying vibrational mode of Ba(2)2+ ions consist of a sharp Lorentzian peak at 1.2 THz superimposed on a broad tail weighted in the lower frequency regime around 1.0 THz. With decreasing temperature, an unexpected linewidth broadening of the phonon peak is observed, together with monotonic softening of the phonon peak and enhancement of the tail structure. These observed anomalies are discussed in terms of impurity scattering effects on the hybridized phonon system of rattling and acoustic phonons.

KW - Clathrates

KW - Hybridized phonon system

KW - Phonon-impurity interactions

KW - Rattling phonons

KW - THz time-domain spectroscopy

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