Experimental Band Structure and Temperature-Dependent Magnetic Exchange Splitting of Nickel Using Angle-Resolved Photoemission

Using angle-resolved photoemission and synchrotron radiation, we have determined the energy-versus-momentum valence-band dispersion relations for a Ni(111) crystal. The temperature-dependent ferromagnetic exchange splitting has been directly observed. Both the $d$-band width (∼3.4 eV at $L$) and exchange splitting (0.31 eV) are much smaller than theoretical estimates (∼4.5 eV wide at $L$ with ∼0.7-eV splitting, respectively, at 293 K).