Effect of Co substitution on the magnetic properties in Fe1−x Co x Ga3

We investigated the effect of Co substitution in Fe1−x Co x Ga3 by means of electric resistivity and magnetic measurements. Nearly ferromagnetic behaviors were observed in Fe1−x Co x Ga3 system by the chemical substitution of Co for Fe in diamagnetic mother compound FeGa3, accompanying with a semiconducting to metallic transition. With the substitution of Co, the magnetization of Fe1−x Co x Ga3 increases first, and then decreases and finally it becomes diamagnetic. The magnetic properties of Fe1−x Co x Ga3 were analyzed in terms of self-consistent renormalization (SCR) theory and Takahashi's theory. The spin-fluctuation parameters, fourth order expansion coefficients of magnetic free energy (), the magnetic susceptibility in the ground state X(0), the spectral widths of the spin fluctuation spectrum T 0 and Ta in the frequency and wave-number spaces, respectively, were estimated from the parameters derived from magnetic measurements. The magnetic properties of Fe1−x Co x Ga3 can be understood almost quantitatively by the SCR theory and Takahashi's theory of spin fluctuations.