Magnetic structure of CeRhIn5 under magnetic field

The magnetically ordered ground state of CeRhIn5 at ambient pressure and zero magnetic field is an incommensurate helicoidal phase with the propagation vector k = (1/2, 1/2, 0.298) and the magnetic moment in the basal plane of the tetragonal structure. We determined by neutron diffraction the two different magnetically ordered phases of CeRhIn5 evidenced by bulk measurements under applied magnetic field in the basal plane. The low temperature high magnetic phase corresponds to a commensurate sine-wave structure of the magnetization with k = (1/2, 1/2, 1/4). At high temperature, the phase is incommensurate with k = (1/2, 1/2, 0.298) and a possible small ellipticity. The propagation vector of this phase is the same as that of the zero-field structure.