1Department of Physics and Center for Advanced Quantum Studies, Beijing Normal University, Beijing 100875 2Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 3Key Laboratory of Neutron Physics, Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621999 4Department of Physics, Shandong University of Technology, Zibo 255049 5Department of Physics and State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027 6Collaborative Innovation Centre of Advanced Microstructures, Nanjing 210093 7Songshan Lake Materials Laboratory, Dongguan 523808 8School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190
Abstract：We use neutron powder diffraction to study the non-superconducting phases of ThFeAsN$_{1-x}$O$_x$ with $x=0.15$, 0.6. In our previous results of the superconducting phase ThFeAsN with $T_{\rm c}=30$ K, no magnetic transition is observed by cooling down to 6 K, and possible oxygen occupancy at the nitrogen site is shown in the refinement [Europhys. Lett. 117 (2017) 57005]. Here in the oxygen doped system ThFeAsN$_{1-x}$O$_x$, two superconducting regions ($0\leqslant x \leqslant 0.1$ and $0.25\leqslant x \leqslant 0.55$) are identified by transport experiments [J. Phys.: Condens. Matter 30 (2018) 255602]. However, within the resolution of our neutron powder diffraction experiment, neither the intermediate doping $x=0.15$ nor the heavily overdoped compound $x=0.6$ shows any magnetic order from 300 K to 4 K. Therefore, while it shares the common phenomenon of two superconducting domes as most 1111-type iron-based superconductors, the magnetically ordered parent compound may not exist in this nitride family.
2019, Vol. 36 
