Experimental study of knight shift trends in the heavy fermion compounds compounds Cerium-M-Indium5 (M=Iridium, Rhodium, Cobalt)

The heavy electron Kondo liquid is an emergent state of condensed matter that displays universal behavior independent of material details. Properties of the heavy electron liquid are best probed by NMR Knight shift measurements, which provide a direct measure of the behavior of the heavy electron liquid that emerges below the Kondo lattice coherence temperature as the lattice of local moments hybridizes with the background conduction electrons. Because the transfer of spectral weight between the localized and itinerant electronic degrees of freedom is gradual, the Kondo liquid typically coexists with the local moment component until the material orders at low temperatures. The two-fluid formula captures this behavior in a broad range of materials in the paramagnetic state. In order to investigate two-fluid behavior and the onset and physical origin of different long range ordered ground states in heavy electron materials, we present Knight shift measurements in Ce1-xLaxCoIn5, CeIrIn5 and CeRhIn5. In CeRhIn5 we find that the anti-ferromagnetic order is preceded by a re-localization of the Kondo liquid, providing independent evidence for a local moment origin of anti-ferromagnetism. In CeIrIn5 we find that the relative weight of the Kondo liquid gradually changes as the sample is rotated while the coherence temperature is unaffected. At high fields around 30T, the coherence temperature in CeIrIn5 is likewise unaffected. The Kondo liquid also remains unaffected at high fields. In Ce1-xLaxCoIn5,we find that the Kondo liquid is due to short range interactions. In this work, we have also found that the two-fluid model is not always the best description of these materials.