The 3d-electronic spin dynamics and the magnetic order in Fe3PO4O3 were investigated by muon spin rotation and relaxation (μSR) and 57Fe M\"ossbauer spectroscopy. Zero-field (ZF)-μSR and 57Fe M\"ossbauer studies confirm static long range magnetic ordering below TN≈ 164\,K. Both transverse-field (TF) and ZF-μSR results evidence 100\% magnetic volume fraction in the ordered state. The ZF-μSR time spectra can be best described by a Bessel function, which is consistent with the helical magnetic structure proposed by neutron scattering experiments. The M\"ossbauer spectra are described in detail by considering the specific angular distribution of the local hyperfine field Bhyp with respect to the local electric field gradient. The μSR spin-lattice relaxation rate exhibits two peaks: One at the magnetic ordering temperature related to critical magnetic fluctuations and another peak at 35\,K signaling the presence of a secondary low energy scale in Fe3PO4O3.
@article{arxiv.1707.07433,
title = {Magnetic order and spin dynamics in the helical magnetic system Fe$_3$PO$_4$O$_3$},
author = {R. Sarkar and S. Kamusella and S. A. Braeuninger and S. Holenstein and J. -C. Orain and H. Luetkens and V. Grinenko and M. J. Tarne and J. R. Neilson and K. A. Ross and H. -H. Klauss},
journal= {arXiv preprint arXiv:1707.07433},
year = {2017}
}