Critical Behavior ofd-Band Photoelectrons Near the Curie Temperature of Nickel

We have measured the temperature dependence of photoelectron energy distributions from nickel for T=100-400^∘ C. An anomalous critical behavior in the d-band peak energy versus temperature was observed in the vicinity of the Curie temperature (TC=358^∘ C). A comparison of the temperature variation of d-band photoelectrons from nickel and palladium indicates at least partial agreement with band-structure calculations. A lower limit of the exchange splitting δEₑₓ≈0.2-0.3 eV is estimated from the experimental data.