Strong Coupling of Rattling Phonon to Conduction Electrons in Semimetallic Type-I Clathrate Ba8Ga16Sn30

Author(s)

Tou, Hideki ^[1] ; Sonoda, Kanto ^[1] ; Furumoto, Kazuya ^[1] ; Kotegawa, Hisashi ^[1] ; Suekuni, Koichiro ^[2] ; Avila, Marcos A. ^[3] ; Takabatake, Toshiro ^{[4, 5]}

Affiliation

^[1] Kobe Univ, Grad Sch Sci, Dept Phys, Kobe, Hyogo 6578501 - Japan

^[2] Japan Adv Inst Sci & Technol, Sch Mat Sci, Nomi, Ishikawa 9231292 - Japan

^[3] Univ Fed ABC, CCNH, BR-09210580 Santo Andre, SP - Brazil

^[4] Hiroshima Univ, Inst Adv Mat Res, Hiroshima 7398530 - Japan

^[5] ADSM, Dept Quantum Matter, Hiroshima 7398530 - Japan

• Document type: Journal article
• Source: JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN; v. 82, n. 11 NOV 2013.
• Web of Science Citations: 4

Abstract

We report studies of Sn-117,Sn-119 and Ga-69,Ga-71 nuclear magnetic resonance (NMR) to investigate electron-phonon interactions due to the off-center rattling of Ba atoms in the semi-metallic type-I Ba8Ga16Sn30 clathrate with n-type charge carriers in the temperature range of 0.4-200 K. The Ga NMR spin-lattice relaxation rate has an anomalous enhancement at approximately 10 K, indicating that the Ba atoms exhibit thermal rattling motion in an anharmonic potential. From calculations using a two-phonon Raman process model for a one-dimensional anharmonic Hamiltonian within a quasi-harmonic approximation, significant broadening of the phonon lifetime and softening of the phonon frequency are found to be essential to reproduce the temperature dependence of the NMR spin-lattice relaxation rate. The characteristic energy of the renormalized phonon frequency omega(r) approximate to 21K was obtained for the rattling state, in agreement with the values estimated by heat capacity analysis and other techniques. These results point to strong coupling of the rattling phonon to conduction electrons in semimetallic type-I Ba8Ga16Sn30. (AU)

• FAPESP's process: 12/17562-9 - Preparation of oriented single crystals for studies on electronic, magnetic and thermal anisotropies
• Grantee: Marcos de Abreu Avila
• Support Opportunities: Regular Research Grants