Intermediate valence quasicrystals in Yb-based alloys under pressure

高圧下で現れるYb準結晶の中間価数状態

綿貫 徹; 川名 大地*; 町田 晃彦; Tsai, A. P.*

Watanuki, Tetsu; Kawana, Daichi*; Machida, Akihiko; Tsai, A. P.*

A quasiperiodic intermediate-valence system has been demonstrated by applying pressure to an icosahedral Cd-Mg-Yb quasicrystal as well as our previous report on a Cd-Yb quasicrystal. Yb LIII-edge X-ray absorption spectroscopy experiments demonstrate that the Yb valence increases continuously upon compression from the divalent state at ambient pressure to reach a valence of 2.37 at 16.3 GPa. These Yb-based quasiperiodic intermediate-valence systems have the following two characteristic features in comparison with known other quasicrystals; (1) each quasiperiodic lattice point has a charge degree of freedom, (2) the strength of electron correlations can be controlled by pressure.