CeRhIn5 is an itinerant magnet where the Ce3+ spins order in a simple helical phase. We investigate the spin excitations and observe sharp spin waves parameterized by a nearest-neighbor exchange, J(RKKY) = 0.88 +/- 0.05 meV. At higher energies, the spin fluctuations are heavily damped, where single-quasiparticle excitations are replaced by a momentum- and energy-broadened continuum constrained by kinematics of energy and momentum conservation. The delicate energy balance between localized and itinerant characters results in the breakdown of the single-quasiparticle picture in CeRhIn5.
- HIGH-TEMPERATURE SUPERCONDUCTIVITY
- NEUTRON POLARIMETRY