Crossover from spin-waves to diffusive spin excitations in underdoped Ba(Fe${}_{1-x}$Co${}_x$)${}_2$As${}_2$

G. S. Tucker, R. M. Fernandes, D. K. Pratt +12

Using inelastic neutron scattering, we show that the onset of superconductivity in underdoped Ba(Fe${}_{1-x}$Co${}_x$)${}_2$As${}_2$ coincides with a crossover from well-defined spin…