Band parameters of nickel deduced from optical measurements

The gap Δ between the top of the d↑ band and the Fermi level is deduced from optical measurements on a nickel single crystal and found to be ≈50 meV, in agreement with previous estimates. The interpretation of the optical spectrum also suggests that the spin-splitting ΔE_d ? 0.40 eV and that a spin- splitting still exists at temperatures higher than T_C.