Two phase transitions in the tetragonal strongly correlated electron system CeNiAsO were probed by neutron scattering and zero field muon spin rotation. For T<TN1 = 8.7(3) K, a second order phase transition yields an incommensurate spin density wave with wave vector k=(0.44(4),0,0). For T<TN2 = 7.6(3) K, we find co-planar commensurate order with a moment of 0.37(5)μB, reduced to 30% of the saturation moment of the ∣±21⟩ Kramers doublet ground state, which we establish by inelastic neutron scattering. Muon spin rotation in CeNiAs1−xPxO shows the commensurate order only exists for x ≤ 0.1 so the transition at xc = 0.4(1) is from an incommensurate longitudinal spin density wave to a paramagnetic Fermi liquid.
@article{arxiv.1707.09645,
title = {Incommensurate magnetism near quantum criticality in CeNiAsO},
author = {Shan Wu and W. A. Phelan and L. Liu and J. R. Morey and J. A. Tutmaher and J. C. Neuefeind and M. Feygenson and Matthew B. Stone and Ashfia Huq and David W. Tam and Benjamin A. Frandsen and Benjamin Trump and Cheng Wan and S. R. Dunsiger and T. M. McQueen and Y. J. Uemura and C. L. Broholm},
journal= {arXiv preprint arXiv:1707.09645},
year = {2019}
}