Coexistence of antiferromagnetism and superconductivity in heavy-fermions systems

Y. Kitaoka; Y. Kawasaki; T. Mito; S. Kawasaki; G. -q. Zheng; K. Ishida; D. Aoki; Y. Haga; R. Settai; Y. Onuki; C. Geibel; F. Steglich

doi:10.1016/S0022-3697(02)00133-6

paper

Coexistence of antiferromagnetism and superconductivity in heavy-fermions systems

arXiv:cond-mat/0201040 · doi:10.1016/S0022-3697(02)00133-6

Abstract

We report the novel pressure(P)-temperature(T) phase diagrams of antiferromagnetism (AF) and superconductivity (SC) in CeRhIn $_{5}$ , CeIn $_{3}$ and CeCu $_{2}$ Si $_{2}$ revealed by the NQR measurement. In the itinerant helical magnet CeRhIn $_{5}$ , we found that the NÃ©el temperature $T_{N}$ is reduced at $P \geq$ 1.23 GPa with an emergent pseudogap behavior. The coexistence of AF and SC is found in a narrow P range of 1.63 - 1.75 GPa, followed by the onset of SC with line-node gap over a wide P window 2.1 - 5 GPa. In CeIn $_{3}$ , the localized magnetic character is robust against the application of pressure up to $P \sim$ 1.9 GPa, beyond which the system evolves into an itinerant regime in which the resistive superconducting phase emerges. We discuss the relationship between the phase diagram and the magnetic fluctuations. In CeCu $_{2}$ Si $_{2}$ , the SC and AF coexist on a microscopic level once its lattice parameter is expanded. We remark that the underlying marginal antiferromagnetic state is due to collective magnetic excitations in the superconducting state in CeCu $_{2}$ Si $_{2}$ . An interplay between AF and SC is discussed on the SO(5) scenario that unifies AF and SC. We suggest that the SC and AF in CeCu $_{2}$ Si $_{2}$ have a common mechanism.

6 pages, 5 figures, proceeding of ISSP2001