Magnetic Order in Ce_(0.95)Nd_(0.05)CoIn_5: The Q-Phase at Zero Magnetic Field

摘要

We report neutron scattering experiment results revealing the nature of the magnetic order occurring in the heavy fermion superconductor Ce_(0.95)Nd_(0.05)CoIn)5. In this system, an antiferromagnetic state is stabilized at a temperature below the superconducting transition one. We evidence that it is an incommensurate order and its propagation vector is found to be identical to that of the magnetic field induced antiferromagnetic order occurring in the stoichiometric superconductor CeCoIn_5, the so-called Q-phase. The commonality between these two cases suggests that d-wave superconductivity is playing a key role for the formation of this kind of magnetic order. The proposed mechanism is the enhancement of the nesting condition by an order parameter with nodes in the nesting area.