Field-induced ferromagnetic structure in Er2Ni2Pb

We have studied the effect of magnetic fields up to 4.5 T on the ground-state structure in Er2Ni2Pb using powder neutron diffraction measurements at low temperatures. The zero-field magnetic state that itself is not uniform and consists of different magnetic phases is rather unstable against the magnetic field. As the field is increased, the magnetic reflections of the zero-field structure disappear and a new magnetic phase with commensurate propagation vector is clearly observed in a field of 0.5 T. At higher fields a ferromagnetic state is established in Er2Ni2Pb, which can be fully described only by a model that combines at least two irreducible representations. The refined Er magnetic moment magnitude of 9.10 ± 0.07 μB is very close to the Er3+ free ion value of 9.0 μB.