Crystal growth, electronic structure, and properties of Ni-substituted FeGa3

Abstract

Crystals of the Fe1−xNixGa3 limited solid solution (x<0.045) have been grown from gallium flux. We have explored the electronic structure as well as magnetic and thermoelectric properties of Fe0.975Ni0.025Ga3 in comparison with Fe0.95Co0.05Ga3, following the rigid band approach and assuming that one Ni atom donates twice the number of electrons as one Co atom. However, important differences between the Co- and Ni-doped compounds are found below 620K, which is the temperature of the metal-to-insulator transition for both compounds. We have found that Fe0.975Ni0.025Ga3 displays lower degree of spatial inhomogeneity on the local level and exhibits diamagnetic behavior with a broad shallow minimum in the magnetic susceptibility near 35K, in sharp contrast with the Curie–Weiss paramagnetism of Fe0.95Co0.05Ga3. Transport measurements have shown the maximum of the thermoelectric figure-of-merit ZT of 0.09 and 0.14 at 620K for Fe0.975Ni0.025Ga3 and Fe0.95Co0.05Ga3, respectively.