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Journal Articles

Thermal expansion of a Au-Al-Yb intermediate valence quasicrystal

Watanuki, Tetsu; Kashimoto, Shiro*; Ishimasa, Tsutomu*; Machida, Akihiko; Yamamoto, Shin*; Tanaka, Yukinori*; Mizumaki, Masaichiro*; Kawamura, Naomi*; Watanabe, Shinji*

Solid State Communications, 211, p.19 - 22, 2015/06

 Times Cited Count:7 Percentile:32.26(Physics, Condensed Matter)

The thermal expansion of a Au-Al-Yb intermediate-valence quasicrystal has been studied by X-ray diffraction measurements. We have found anomalous thermal expansion behavior, namely zero thermal expansion below 50 K. By comparison with an isostructural Au-Al-Tm quasicrystal, the contribution of the Yb valence variation was extracted, and it was shown that its negative thermal expansion component due to the valence shift toward the divalent state by cooling compensated for the positive thermal expansion of the original lattice.

Journal Articles

Lattice dynamics of the Zn-Mg-Sc icosahedral quasicrystal and its Zn-Sc periodic 1/1 approximant

de Boissieu, M.*; Francoual, S.*; Minalkovi$v{c}$, M.*; Shibata, Kaoru; Baron, A. Q. R.*; Sidis, Y.*; Ishimasa, Tsutomu*; Wu, D.*; Lograsso, T.*; Regnault, L.-P.*; et al.

Nature Materials, 6(12), p.977 - 984, 2007/12

 Times Cited Count:39 Percentile:81.37(Chemistry, Physical)

We have carried out inelastic X-ray and neutron scattering experiments on single-grain samples of the Zn-Mg-Sc icosahedral quasicrystal and of the Zn-Sc periodic cubic 1/1 approximant, with the aim of studying the respective influence of the local order and the long-range order (periodic or quasiperiodic) on lattice dynamics. Besides the overall similarities and the existence of a pseudo-gap in the transverse dispersion relation, marked difference are observed, the pseudo-gap being larger and better defined in the approximant than in the quasicrystal. These results are compared with simulations on atomic models and using oscillating pair potentials, and the simulations reproduce in detail the experimental results.

Oral presentation

Intermediate-valence quasicrystals of Yb based alloys

Watanuki, Tetsu; Kawana, Daichi*; Machida, Akihiko; Tsai, A. P.*; Tanaka, Yukinori*; Kashimoto, Shiro*; Ishimasa, Tsutomu*

no journal, , 

no abstracts in English

Oral presentation

Intermediate-valence quasicrystals of Yb based alloys

Watanuki, Tetsu; Kawana, Daichi*; Machida, Akihiko; Tsai, A. P.*; Kashimoto, Shiro*; Tanaka, Yukinori*; Ishimasa, Tsutomu*

no journal, , 

no abstracts in English

Oral presentation

Intermediate-valence Yb-based quasicrystals

Watanuki, Tetsu; Kawana, Daichi*; Machida, Akihiko; Tsai, A. P.*; Kashimoto, Shiro*; Tanaka, Yukinori*; Ishimasa, Tsutomu*; Yamazaki, Teruo*; Sato, Taku*

no journal, , 

Quasiperiodic intermediate-valence systems were prepared by applying pressure to Yb-based quasicrystals. In these systems, each quasiperiodic lattice point has a charge degree of freedom. Synchrotron radiation X-ray absorption spectroscopy experiments near the Yb L3-edge demonstrate that the Yb valence in a Cd-Yb icosahedral quasicrystal increases continuously upon compression from a divalent state at ambient pressure and reaches 2.33 at 31.7 GPa, where the quasiperiodically arranged Yb ions take a valence fluctuation state. For the case of a Cd-Mg-Yb icosahedral quasicrystal, the Yb valence reaches a value of 2.71 at 57.6 GPa. By following the trend of Yb-based intermediate-valence crystalline compounds, this large valence increase suggests that the 4f electron system in this quasicrystal varies from a valence fluctuation regime to a strong correlated electron regime. Additionally, we have recently found that Au-Al-Yb icosahedral quasicrystal is an IV compound at ambient pressure.

Oral presentation

Intermediate-valence Yb-based quasicrystals, measurements of the valence and physical properties

Watanuki, Tetsu; Kawana, Daichi*; Machida, Akihiko; Kashimoto, Shiro*; Tanaka, Yukinori*; Ishimasa, Tsutomu*; Yamazaki, Teruo*; Sato, Taku*; Tsai, A. P.*

no journal, , 

no abstracts in English

Oral presentation

Intermediate-valence icosahedral Au-Al-Yb quasicrystal

Watanuki, Tetsu; Kashimoto, Shiro*; Yamazaki, Teruo*; Kawana, Daichi*; Machida, Akihiko; Tanaka, Yukinori*; Ishimasa, Tsutomu*; Sato, Taku*

no journal, , 

A quasiperiodic, intermediate-valence (IV) system is realized in an icosahedral Au-Al-Yb quasicrystal. X-ray absorption spectroscopy near the Yb L3-edge indicates that quasiperiodically arranged Yb ions assume a mean valence of 2.61, between a divalent state (4f14, J = 0) and a trivalent one (4f13, J = 7/2). Magnetization measurements demonstrate that the 4f holes in this quasicrystal have a localized character. The magnetic susceptibility shows a Curie-Weiss behavior above 100 K with an effective magnetic moment of 3.81 muB per Yb. Moreover, a crystalline approximant to this quasicrystal is an IV compound. We propose a heterogeneous IV model for the quasicrystal, whereas the crystalline approximant is most likely a homogeneous IV system. At temperatures below 10 K, specific heat and magnetization measurements reveal non-Fermi-liquid behavior in both the quasicrystal and its crystalline approximant without either doping, pressure, or field tuning.

Oral presentation

Thermal expansion of intermediate-valence Au-Al-Yb quasicrystal

Watanuki, Tetsu; Kashimoto, Shiro*; Yamamoto, Shin*; Machida, Akihiko; Ishimasa, Tsutomu*

no journal, , 

no abstracts in English

Oral presentation

Pressure dependence of Yb valence in an intermediate-valence Au-Al-Yb-quasicrystals

Watanuki, Tetsu; Machida, Akihiko; Kawana, Daichi*; Tanaka, Yukinori*; Ishimasa, Tsutomu*

no journal, , 

no abstracts in English

Oral presentation

Thermal expansion of intermediate-valence Au-Al-Yb quasicrystal

Watanuki, Tetsu; Kashimoto, Shiro*; Yamamoto, Shin*; Machida, Akihiko; Ishimasa, Tsutomu*

no journal, , 

no abstracts in English

Oral presentation

Pressure dependence of Yb valence in an intermediate-valence Au-Al-Yb- Quasicrystal

Watanuki, Tetsu; Machida, Akihiko; Kawana, Daichi*; Kashimoto, Shiro*; Tanaka, Yukinori*; Ishimasa, Tsutomu*

no journal, , 

no abstracts in English

Oral presentation

Intermediate-valence Yb-based quasicrystals and approximants

Watanuki, Tetsu; Yamada, Tsunetomo*; Nakamura, Yoko*; Tanaka, Yukinori*; Machida, Akihiko; Tsai, A. P.*; Ishimasa, Tsutomu*

no journal, , 

no abstracts in English

Oral presentation

Magnetic field effects on the Yb valence of a Yb-Au-Al quasicrystal at low temperatures

Watanuki, Tetsu; Mizumaki, Masaichiro*; Kawamura, Naomi*; Watanabe, Shinji*; Nitta, Kiyofumi*; Tanaka, Yukinori*; Ishimasa, Tsutomu*

no journal, , 

no abstracts in English

Oral presentation

Temperature variation of Yb valence in intermediate-valence Yb-based crystalline approximants

Watanuki, Tetsu; Yamada, Tsunetomo*; Nakamura, Yoko*; Tanaka, Yukinori*; Nitta, Kiyofumi*; Mizumaki, Masaichiro*; Machida, Akihiko; Tsai, A. P.*; Ishimasa, Tsutomu*

no journal, , 

no abstracts in English

Oral presentation

Intermediate-valence Yb-based quasicrystals and approximants

Watanuki, Tetsu; Kawana, Daichi*; Machida, Akihiko; Kashimoto, Shiro*; Ishimasa, Tsutomu*; Tsai, A. P.*

no journal, , 

Oral presentation

Magnetic field effects on the Yb valence of a Yb-Au-Al quasicrystal at low temperatures

Watanuki, Tetsu; Mizumaki, Masaichiro*; Kawamura, Naomi*; Watanabe, Shinji*; Nitta, Kiyofumi*; Tanaka, Yukinori*; Ishimasa, Tsutomu*

no journal, , 

no abstracts in English

16 (Records 1-16 displayed on this page)
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