A high energy Compton scattering study of magnetocaloric HoAl2

• Measured first ever experimental Compton profile (CP) of HoAl2.
• Highlighted CP method for finding charge reorganisation in compounds.
• Computed first ever energy bands and DOS of HoAl2 using SPR-KKR method.
• Predicted charge transfer in HoAl2 using CPs and integrated DOS.
• Discussed state-of-art charge transfer method using differences in DOS.

We present the first-ever Compton profile of HoAl2 at an intermediate resolution of 0.36 a.u. using a 740 GBq 137Cs Compton spectrometer. Charge reorganization on the formation of compound is depicted by significant deviation between the experimental Compton profile of HoAl2 and superposition profile (deduced from individual Compton measurements of Ho and Al). Further analysis of experimental momentum densities of HoAl2 shows a charge transfer of 0.32±0.03e‾ from Al→Ho. The electronic occupancies obtained from the present measurements are very close to those computed using spin-polarized relativistic Korringa–Kohn–Rostoker method. Electronic properties of HoAl2 are also explained on the basis of energy bands and integrated density of states.