While it is established that the pinch point scattering pattern in spin ice arises from an emergent coulomb phase associated with magnetic moment that is divergence-free, more complex Hamiltonians can introduce a divergence-full part. If these two parts remain decoupled, they give rise to the co-existence of distinct features. Here we show that the moment in Nd2Hf2O7 forms a static long-range ordered ground state, a flat, gapped pinch point excitation and dispersive excitations. These results confirm recent theories which predict that the dispersive modes, which arise from the divergence-full moment, host a pinch point pattern of their own, observed experimentally as `half-moons'.
@article{arxiv.2208.12369,
title = {Pinch points and half-moons in dipolar-octupolar Nd$_2$Hf$_2$O$_7$},
author = {A. Samartzis and J. Xu and V. K. Anand and A. T. M. N. Islam and J. Ollivier and Y. Su and B. Lake},
journal= {arXiv preprint arXiv:2208.12369},
year = {2022}
}