Electronic structure of the strongly-exchange-enhanced paramagnetNi3Ga

The electronic structure of the incipient ferromagnet ${\mathrm{Ni}}_3$Ga has been studied by means of the de Haas–van Alphen technique in the magnetic field and temperature ranges 10≤H≤100 kG and 0.38≤T≤4.2 K, respectively. Concurrently, first-principles energy bands have been calculated by means of the linear-muffin-tin-orbital method. The calculated Fermi surface consists of four concentric hole sheets centered on the point Γ of the simple-cubic Brillouin zone. de Haas–van Alphen frequency branches in close agreement with those expected for each of these four sheets have been observed for field directions both in the (100) and (11¯0) planes. The cyclotron masses of these branches, as well as the linear coefficient γ of the electronic heat capacity, are, however, greater than predicted by our band model, by a factor of between 1.5 and 2.7. Comparison of the measured and calculated magnetic susceptibility yields a Stoner enhancement factor of 98, the highest so far reported in an ordered paramagnetic transition metal, and an enhancement of the quadratic coefficient of the inverse susceptibility α=∂${\chi }^{\mathrm{-}1}$(T)/∂($T^2$), of over 8. The strong renormalization of γ and α points to the importance of exchange-enhanced spin fluctuations for this material, as previously reported in the weak itinerant-electron ferromagnet ${\mathrm{Ni}}_3$Al.