Evolution from antiferromagnetic order to spin-glass state in Fe1.05 − xCuxTe system

Abstract

Well understanding about the physical properties of FeTe compound, as a parent of superconducting Fe(Te, Se) system, is very important for exploring superconducting mechanism in the Fe-based superconductors. Here, based on the transport and magnetization measurements, we report the Cu doping effects on the physical properties of Fe1.05Te compound. We found that in the undoped sample, an antiferromagnetic (AFM) transition accompanying a semiconductor–metal transition occurs at 70 K. With the increase of Cu content x, the AFM transition temperature decreases monotonously at first. When x⩾0.05, both the metallic behavior and long-range AFM ordering disappear. Meanwhile, a spin-glass state emerges at low temperatures. The evolution of the transport and the magnetic properties with the Cu content x is summarized and a phase diagram is proposed. Our results indicate that a local spin picture may be more appropriate than an itinerant model for the Fe1.05Te compound.