Electronic Structure in Heavy Fermion Compound UPd2Al3 Through Directional Compton Profile Measurement

We have measured directional Compton profiles on the (0001) plane in the UPd2Al3 single crystal with hexagonal symmetry in order to investigate the change in electronic structure related to the crossover phenomenon between the itinerant and localized states of 5f electrons. Two-dimensional electron occupation number densities (2D-EONDs), which are the projection of Fermi volumes on the view plane, are obtained at 20 and 100K through electron momentum reconstruction and Lock-Crisp-West folding analysis. We have also derived theoretical 2D-EONDs from the results of band calculations with the linear muffin-tin orbital method for comparison. The experimental 2D-EONDs at 20 and 100K are well described by the theoretical ones based on the itinerant and localized models of 5f electrons, respectively. Therefore, the contributions of 5f electrons to the Fermi surfaces in the itinerant state are verified around Gamma (A) points in the first Brillouin zone through comparison.