Effect of Disorder on Fermi surface in Heavy Electron Systems

TL;DR

This study investigates how substitutional disorder affects the Fermi surface in heavy-fermion systems using DMFT and CPA, revealing size changes, broadening effects, and a metamagnetic transition in Ce-La alloys.

Contribution

It applies combined DMFT and CPA methods to analyze Fermi surface evolution in disordered heavy-fermion systems, providing new insights into disorder effects.

Findings

Fermi surface size increases as Ce concentration decreases.

Fermi surface broadens with La substitution but remains at the same position.

Dingle temperature peaks around equal Ce and La concentrations.

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 Ce{x}La{1-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 such x 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.