Magnetic properties of ferromagnetic Heusler alloy Co2NbGa

•The stoichiometric compound Co2NbGa crystallizes in the Heusler-type structure.•Co2NbGa is ferromagnetic below the Curie temperature of 351 K.•The spontaneous magnetic moment at 5 K of Co2NbGa is 1.81 μB/f.u.•The spectral parameters T0 of the spin fluctuation are estimated to be 2.1 × 103 K.•The spectral parameters TA of the spin fluctuation are estimated to be 4.7 × 103 K.•The TA value estimated from the Ms(T)2 vs. T2 curve is 6.6 × 103 K.•The field-induced magnetization M4 around TC is found to be proportional to H/M.