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 manybody 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 nanoscale: 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 finitesize spectra of these devices as a function of the coupling between the impurity spin and a finitesize 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 heavyfermion materials: Experiments on many heavyfermion metals, e.g. Ce_{x}La_{1x}CoIn_{5} have allowed a detailed study of the evolution from a Kondo lattice to the Kondo impurity problem as the concentration of fmoments (e.g. Ce concentration for CeLaCoIn_5) is varied. In particular as fmoments are randomly depleted, the heavy Fermiliquid phase will eventually become a dilute singleimpurity Fermiliquid. This evolution from one Fermiliquid into another is described by a fascinating interplay of randomness and strong electronelectron interactions.
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