We have investigated the ground state properties of polycrystalline CeCoAsO by means of magnetization, specific heat and solid state NMR. Susceptibility and specific-heat measurements suggest a ferromagnetic order at about, TC=75 K. No further transitions are found down to 2 K. At 6.5 K a complex Schottky type of anomaly shows up in the specific heat results. The interplay between Ce-4f and Co-3d magnetism being responsible for that anomaly is discussed. Furthermore 75As NMR investigations have been performed to probe the magnetism on a microscopic scale. As-NMR spectra are analysed in terms of first and second order quadrupolar interaction. The anisotropic shift component Kab and Kc could be derived from the 75As powder spectra. Towards lower temperature a strong shift anisotropy was found. Nonetheless Kiso tracks the bulk susceptibility down to T=50 K very well. Furthermore the presence of weak correlations among the Ce ions in the ferromagnetic state is discussed. The observed increase of C/T towards lower temperatures supports this interpretation.
@article{arxiv.1006.5904,
title = {Interplay between Co-3d and Ce-4f magnetism in CeCoAsO},
author = {Rajib Sarkar and Anton Jesche and Cornelius Krellner and Chandan Mazumdar and Asok Poddar and Michael Baenitz and Cristoph Geibel},
journal= {arXiv preprint arXiv:1006.5904},
year = {2015}
}