Mapping out the spin fluctuations in Co-doped LaFeAsO single crystals by NMR

We determine the phase diagram of LaFe$_{1-x}$Co$_x$AsO single crystals by using nuclear magnetic resonance (NMR). Up to a nominal doping $x=0.03$, it follows for F-doped polycrystals. Above samples become superconducting, whereas Co-doping structural and transitions can be observed up $x=0.042$, superconductivity occurs only higher levels with reduced transition temperatures. For dopings $x=0.056$, we find evidence short-range order. By means relaxation-rate measurements, map out fluctuations that reveal interplay nematicity magnetism. nematic ordering, spin in are identical those Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$, suggesting LaFeAsO is result fluctuating density wave as well.