Mössbauer-effect investigations under applied magnetic field and magnetization studies of neptunium intermetallics in their paramagnetic state are reported. It is shown that the bulk and local susceptibilities at 4.2 K (${\mathrm{\chi }}_{\mathrm{B}}$ and ${\mathrm{\chi }}_{\mathrm{L}}$, respectively) agree even for highly hybridized 5f-electron systems. The results indicate dominant orbital contributions to the magnetic moment also for paramagnetic neptunium heavy-fermion compounds. For these Np systems proportionalities between ${\mathrm{\chi }}_{\mathrm{L}}$, ${\mathrm{\chi }}_{\mathrm{B}}$, density of states at the Fermi energy, and the isomer shift are pointed out.

• Received 2 August 1989

DOI:https://doi.org/10.1103/PhysRevLett.63.2413