Charge order and crystal structure below the first-order “metal–insulator” transition in Yb4As3

Abstract Resonant X-ray diffraction results on polycrystalline and single crystal Yb 4 As 3 are reported. The strong resonant enhancement of particular superlattice reflections at temperatures below the first-order phase transition gives direct evidence of one-dimensional charge order. Similar evidence is obtained from the energy dependence of powder diffraction reflections. The quantitative determination of the charge ordering, which does not follow the structural distortion, has direct impact on models describing the unusual electronic and magnetic properties of this material.