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Journal Articles

Intermediate-valence icosahedral Au-Al-Yb quasicrystal

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

Physical Review B, 86(9), p.094201_1 - 094201_6, 2012/09

 Times Cited Count:56 Percentile:89.52(Materials Science, Multidisciplinary)

A quasiperiodic, intermediate-valence (IV) system is realized in an icosahedral Au-Al-Yb quasicrystal. X-ray absorption spectroscopy near the Yb $$L$$$$_{3}$$-edge indicates that quasiperiodically arranged Yb ions assume a mean valence of 2.61, between a divalent state (4$$f$$$$^{14}$$, $$J$$ = 0) and a trivalent one (4$$f$$$$^{13}$$, $$J$$ = 7/2). Magnetization measurements demonstrate that the 4$$f$$ holes in this quasicrystal have a localized character. The magnetic susceptibility shows a Curie-Weiss behavior above $$sim$$100 K with an effective magnetic moment of 3.81 $$mu$$$$_{rm B}$$ 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 $$sim$$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

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.

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