Decoupling neutron resonances from superconducting transition temperatures in NaFe$_{1-x}$Co$_x$As

We report a comprehensive study of the evolution of neutron resonance modes in wide doping range of NaFe$_{1-x}$Co$_x$As. Double resonances, a sharp followed by a broad one, are observed in certain underdoped region. Surprisingly, the sharp resonance energy is nearly unchanged with variation of doping concentrations and therefore $T_c$. In overdoped region without competing phases, single resonance presents and is gradually broadening with further increasing doping. Nevertheless, the resonances peak at the same energy while $T_c$ falls half from slightly overdoped one ($T_c$=18 K) to heavily overdoped one ($T_c$ = 9 K). The decoupling between $E_r$ and $T_c$ indicates unappreciated coherence which had not been predicted by any theoretical models. Our results manifest the distinct multiorbital character in FeSC, guiding a new direction in the pursuit of a generic connection in diversified unconventional superconductors.