Spin dynamics of FeGa${}_{3-x}$Ge${}_x$ studied by Electron Spin Resonance

Abstract

The intermetallic semiconductor FeGa${}_3$ 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 FeGa${}_{3-x}$Ge${}_x$ 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 $\approx 40$~K whereas at higher temperatures an ESR signal as seen in FeGa${}_3$ prevails independent on the Ge-content. The present results show that the ESR of FeGa${}_{3-x}$Ge${}_x$ is an appropriate and direct tool to investigate the evolution of 3d-based itinerant magnetism.

12 pages, 7 figures

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