Spin dynamics of FeGa3-xGex studied by electron spin resonance

The intermetallic semiconductor FeGa3 acquires itinerant ferromagnetism upon electron doping by a partial replacement of Ga with Ge. We studied the electron spin resonance (ESR) of high-quality single crystals of FeGa3-xGex for x from 0 up to 0.162 where ferromagnetic order is observed. For x = 0 we observed a well-defined ESR signal, indicating the presence of pre-formed magnetic moments in the semiconducting phase. Upon Ge doping the occurrence of itinerant magnetism clearly affects the ESR properties below approximate to 40 K, whereas at higher temperatures an ESR signal as seen in FeGa3 prevails independent on the Ge content. The present results show that the ESR of FeGa3-xGex is an appropriate and direct tool to investigate the evolution of 3d-based itinerant magnetism.