Neutron and synchrotron resonant X-ray magnetic scattering (RXMS) complemented by heat capacity and resistivity measurements reveal the evolution of the magnetic structures of Fe and Ce sublattices in single crystal CeFeAsO. The RXMS of magnetic reflections at the Ce LII-edge shows a magnetic transition that is specific to the Ce antiferromagnetic long-range ordering at TCe≈ 4 K with short-range Ce ordering above TCe, whereas neutron diffraction measurements of a few magnetic reflections indicate a transition at T∗≈ 12 K with unusual order parameter. Detailed order parameter measurements on several magnetic reflections by neutrons show a weak anomaly at 4 K which we associate with the Ce ordering. The successive transitions at TCe and T∗ can also be clearly identified by two anomalies in heat capacity and resistivity measurements. The higher transition temperature at T∗≈ 12 K is mainly ascribed to Fe spin reorientation transition, below which Fe spins rotate uniformly and gradually in the \textit{ab} plane. The Fe spin reorientation transition and short-range Ce ordering above TCe reflect the strong Fe-Ce couplings prior to long-range ordering of the Ce. The evolution of the intricate magnetic structures in CeFeAsO going through T∗ and TCe is proposed.
@article{arxiv.1311.1243,
title = {Magnetic structures and the Ce-Fe coupling induced Fe spin reorientation in CeFeAsO single crystal},
author = {Qiang Zhang and Wei Tian and Haifeng Li and Jong-Woo Kim and Jiaqiang Yan and R. William McCallum and Thomas A. Lograsso and Jerel L. Zarestky and Sergey L. Bud'ko and Robert J. McQueeney and David Vaknin},
journal= {arXiv preprint arXiv:1311.1243},
year = {2013}
}