Field induced magnetic moment distribution in the ordered phase of PrFe₄P₁₂

Neutron diffraction experiments have been performed to investigate the electronic phase transitions in the Pr-based filled skutterudite PrFe ₄P₄. This compound undergoes a transition from a characteristic heavy-electron state to a nonmagnetic phase below 6.5 K. Neutron diffraction experiments reveal an antiferromagnetic alignment of the magnetic-field induced dipole moments. The directions of the antiferromagnetic components are considered to be always parallel to the magnetic field applied along either [0 0 1], [1 1 0] or [1 1 1]. This implies that the symmetry of the ordered state can be categorized as Γ₁. This phenomenon is consistent with the scenario of a scalar-type order parameter for the Pr 4f electron state.