un 2 01 2 Emergent states in heavy electron materials

We obtain the conditions necessary for the emergence of various low temperature ordered states (local moment antiferromagnetism, unconventional superconductivity, quantum criticality, and Landau Fermi liquid behavior) in Kondo lattice materials by extending the two-fluid phenomenological theory of heavy electron behavior [1, 2, 3, 4, 5, 6, 7, 8] to incorporate the concept of hybridization effectiveness. We use this expanded framework to present a new phase digram and consistent physical explanation and quantitative description of measured emergent behaviors such as the pressure variation of the onset of local moment antiferromagnetic ordering at TN , the magnitude of the ordered moment, the growth of superconductivity within that ordered state, the location of a quantum critical point, and of a delocalization line in the pressure/temperature phase diagram at which local moments have disappeared and the heavy electron Fermi surface has grown to its maximum size. We apply our model to CeRhIn5 and a number of other heavy electron materials and find good agreement with experiment. Heavy electron materials provide a unique f -electron laboratory for the study of the interplay between localized and itinerant behavior. At comparatively high temperatures, itinerancy emerges as the localized f -electrons collectively reduce their entropy by hybridizing with the conduction electrons to form a new state of matter, an itinerant heavy electron Kondo liquid that displays scaling (non-Landau Fermi liquid) behavior. The emergent Kondo liquid coexists with the hybridized spin liquid that describes the lattice of local moments whose magnitude has been reduced by hybridization until one reaches the comparatively low temperatures at which unconventional superconductivity and hybridized local moment