Crystallographic disorder and electron scattering on structural two-level systems in ZrAs_1.4Se_0.5

Single crystals of ZrAs_1.4Se_0.5 (PbFCl-type structure) were grown by chemical vapour transport. While their thermodynamic and transport properties are typical for ordinary metals, the electrical resistivity exhibits a shallow minimum at low temperatures. Application of strong magnetic fields does not influence this anomaly. The minimum of the resistivity in ZrAs_1.4Se_0.5 apparently originates from interaction between the conduction electrons and structural two-level systems. Significant disorder in the As-Se substructure is inferred from x-ray diffraction and electron microprobe studies.