A study of the Heusler alloy using ultraviolet photoemission spectroscopy

Ultraviolet photoemission spectroscopy has been employed to provide information on the valence band of the Heusler alloy. The contribution of the d bands of Mn and Cu to the density of states has been investigated by means of 3p to 3d resonant enhancement. The valence band extends to 6 eV below the Fermi level, with a main peak at a binding energy of 3.2 eV and a shoulder extending to the Fermi edge. Resonant photoemission indicates that the Mn 3d character extends across the full width of the band. An experimental photoemission spectrum obtained at a photon energy of 40 eV has been compared with a calculated spectrum derived from a theoretical band structure. The main difference occurs in the region 1 - 2 eV below the Fermi level. The calculated spectrum exhibits a peak at a binding energy of 1.5 eV, comprising contributions from both the Cu and Mn 3d bands. There is no evidence of a similar feature in the experimental spectrum.