A study of the Cu2MnAl Heusler alloy using ultraviolet photoemission spectroscopy

Ultraviolet photoemission spectroscopy has been employed to provide information on the valence band of the Cu2MnAl 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.