Evolution of the spin resonance in CeCoIn₅ under magnetic field

The evolution of the magnetic excitation spectrum of the unconventional superconductor CeCoIn$_{5}$ was studied by inelastic neutron scattering as a function of magnetic field applied in the [1, -1, 0] direction. The spin resonance characteristic of the superconducting states was observed up to about $H_{c2}$/2 : it is still centered at (1/2, 1/2, 1/2) when the magnetic field increases while its characteristic energy decreases and its lineshape substantially broadens.