Photoemission study of the Laves-phase compounds YMn₂ and Y_0.97Sc_0.03Mn₂

A small amount of Sc substitution for Y in the antiferromagnetic metal YMn₂ results in a paramagnetic metal with a strongly enhanced electronic specific heat. We have studied the electronic structure of YMn₂ and Y_0.97Sc_0.03Mn₂ by photoemission spectroscopy. The spectra of YMn₂ taken above and below the Néel temperature did not show appreciable difference, and the spectra of YMn₂ and Y_0.97Sc_0.03Mn₂ were similar to each other. The photoemission spectra of the antiferromagnetic phase are well explained by band-structure calculation on the antiferromagnetic state while those of the paramagnetic phase are not explained by band-structure calculation on the paramagnetic state. These observations suggest that there are strong antiferromagnetic correlations in the paramagnetic phase. For the paramagnetic phase, agreement between experiment and calculation could be considerably improved by applying a model self-energy correction to the band density of states.