On the ground-state magnetic structure in Er2Ni2Pb

Abstract

We have studied the unusual low-temperature magnetic phase of Er2Ni2Pb using powder neutron diffraction measurements in zero field down to 460 mK. Our previous neutron diffraction experiments down to 1.5 K showed that magnetic Bragg reflections seen in Er2Ni2Pb can be indexed by several propagation vectors that partially coexist. All the incommensurate propagation vectors seemed to disappear in the low temperature limit. The present study, however, shows that reflections belonging to the propagation vector q’ = (0.47 0 1/2) do not disappear but remain present down to 460 mK. This highly unexpected result suggests that the magnetic structure described by this propagation vector might not be a simple sine-wave modulation. One interesting possibility here is a spin-slip structure as the ground state.