We investigate the temperature dependence of the spin dynamics in the pyrochlore magnet Nd2Zr2O7 by neutron scattering experiments. At low temperature, this material undergoes a transition towards an "all in - all out" antiferromagnetic phase and the spin dynamics encompass a dispersion-less mode, characterized by a dynamical spin ice structure factor. Unexpectedly, this mode is found to survive above TN≈300 mK. Concomitantly, elastic correlations of the spin ice type develop. These are the signatures of a peculiar correlated paramagnetic phase which can be considered as a new example of Coulomb phase. Our observations near TN do not reproduce the signatures expected for a Higgs transition, but show reminiscent features of the "all in - all out" order superimposed on a Coulomb phase.
@article{arxiv.2101.09049,
title = {Spin dynamics and unconventional Coulomb phase in Nd$_2$Zr$_2$O$_7$},
author = {M. Léger and E. Lhotel and M. Ciomaga Hatnean and J. Ollivier and A. R. Wildes and S. Raymond and E. Ressouche and G. Balakrishnan and S. Petit},
journal= {arXiv preprint arXiv:2101.09049},
year = {2021}
}