Intermediate-Valence Quasicrystals of Yb-Based Alloys Under Pressure

Abstract

A quasiperiodic intermediate-valence system is demonstrated by applying pressure to an icosahedral Cd-Mg-Yb quasicrystal as well as our previous report on a Cd-Yb quasicrystal [Phys. Rev. B 81 (2010) 220202(R)]. Yb L III -edge x-ray absorption spectroscopy experiments demonstrate that the Yb valence increases continuously upon compression from the divalent state at ambient pressure, and reaches a valence of 2.37 at 16.3 GPa. Unlike other known quasicrystals, these Yb-based quasiperiodic intermediate-valence systems have the following two characteristics. 1) Each quasiperiodic lattice point has a charge degree of freedom, and 2) pressure can control the strength of the electron correlations.