Effect of Disorder on Fermi Surface in Heavy Electron Systems

Abstract

The Kondo lattice model with substitutional disorder is studied with attention to the size of the Fermi surface and the associated Dingle temperature. The model serves for understanding heavy-fermion Ce compounds alloyed with La according to substitution CexLa1−x. The Fermi surface is identified from the steepest change of the momentum distribution of conduction electrons, and is derived at low enough temperature by the dynamical mean-field theory (DMFT) combined with the coherent potential approximation (CPA). The Fermi surface without magnetic field increases in size with decreasing x from x = 1 (Ce end), and disappears at suchx that gives the same number of localized spins as that of conduction electrons. From the opposite limit of x = 0 (La end), the Fermi surface broadens quickly as x increases, but stays at the same position as that of the La end. With increasing magnetic field, a metamagnetic transition occurs, and the Fermi surface above the critical field changes continuously across the whole range of x. The Dingle temperature takes a maximum around x = 0.5. Implication of the results to experimental observation is discussed.

Lifshitz Transition in Kondo Alloys

“…This mechanism may also provide a possible scenario for the origin of the NFL properties observed recently in Ce x La 1−x PtIn [47]. A difference (transition or crossover) between dilute Kondo system and a dense heavy fermion had also been suggested by other theoretical methods, including finite size calculations [29], quantum Monte Carlo simulations [48,49] and Gutzwiller approximation [50]. We propose to analyze more systematically Kondo alloys in order to find other examples of NFL behavior of this type.…”

Fermi Surface Properties, Metamagnetic Transition and Quantum Phase Transition of CeRu2Si2 and Its Alloys Probed by the dHvA Effect

“…182 This result could be brought about by using the Kondo model where the charge degrees of freedom is quenched. Although we might obtain a different result by using the Anderson model, we suspect that the change in the Fermi edge could be smaller than the prediction of the rigid band model for normal metals where the f electron of Ce is assumed to fill the conduction band.…”

Breakdown of coherence in Kondo alloys: crucial role of concentration versus band filling

“…This microscopic scenario should be relevent for understanding the origine of unusual properties in several Kondo alloy systems like Ce x La 1x Cu 5.62 Au 0. 38 . At finite Z, the statistical diversity of local neighborhood should transform the transition into a crossover.…”