Harvard Condensed Matter Theory Seminars

Abstract

Ribhu Kaul, Duke University

From the Mesoscopic Kondo Impurity Problem to the Kondo Lattice

I will discuss recent work we have done concerned with the parametric evolution of two quantum many-body systems. These are however relevant to very different kinds of experiments.

1) In the first half, I will talk about work we have done on the interplay of interference and interactions on the nano-scale: In particular, I will consider the problem of a single quantum spin confined to a metallic host. I will present calculations on the evolution of the finite-size spectra of these devices as a function of the coupling between the impurity spin and a finite-size bath, using both analytic arguments and numerical techniques. Finally, I will show how these predictions can be measured in experiments well within the reach of current technology.

2) In the second half, I will present a theoretical study of "randomly depleted Kondo lattices", relevant to heavy-fermion materials: Experiments on many heavy-fermion metals, e.g. Ce_{x}La_{1-x}CoIn_{5} have allowed a detailed study of the evolution from a Kondo lattice to the Kondo impurity problem as the concentration of f-moments (e.g. Ce concentration for CeLaCoIn_5) is varied. In particular as f-moments are randomly depleted, the heavy Fermi-liquid phase will eventually become a dilute single-impurity Fermi-liquid. This evolution from one Fermi-liquid into another is described by a fascinating interplay of randomness and strong electron-electron interactions.