Supersymmetry and Theory of Heavy-Fermions

TL;DR

This paper introduces a novel theoretical approach to the Kondo lattice that captures both the Kondo effect and local magnetism, revealing a magnetic instability and complex dynamical susceptibility features.

Contribution

It presents an original representation of impurity spins combining fermionic and bosonic variables, improving predictions of magnetic instability and Fermi surface properties.

Findings

Magnetic instability at J_c/D=0.67, an improvement over previous theories.

Dynamical susceptibility shows an inelastic peak alongside Fermi liquid behavior.

Fermi surface includes n_c+1 states, indicating a large Fermi surface.

Abstract

We propose a new approach to the Kondo lattice in order to describe simultaneously the Kondo effect and the local magnetism. This approach relies on an original representation of the $S=1/2$ impurity spin in which the different degrees of freedom are represented by fermionic as well as bosonic variables. The magnetic instability is found at $J_c/D =0.67$ in definite improvement compared to usual fermionic mean- field theories. The dynamical susceptibility contains an inelastic peak in addition to the standard Lindhard-type Fermi liquid contribution. The Fermi surface sum rule includes $n_c+1$ states corresponding to large Fermi surfaces.