Hyperfine Interactions in the Heavy Fermion CeMIn_5 Systems

Abstract

The CeMIn_5 heavy fermion compounds have attracted enormous interest since their discovery six years ago. These materials exhibit a rich spectrum of unusual correlated electron behavior, and may be an ideal model for the high temperature superconductors. As many of these systems are either antiferromagnets, or lie close to an antiferromagnetic phase boundary, it is crucial to understand the behavior of the dynamic and static magnetism. Since neutron scattering is difficult in these materials, often the primary source of information about the magnetic fluctuations is Nuclear Magnetic Resonance (NMR). Therefore, it is crucial to have a detailed understanding of how the nuclear moments interact with conduction electrons and the local moments present in these systems. Here we present a detailed analysis of the hyperfine coupling based on anisotropic hyperfine coupling tensors between nuclear moments and local moments. Because the couplings are symmetric with respect to bond axes rather than crystal lattice directions, the nuclear sites can experience non-vanishing hyperfine fields even in high symmetry sites.