2 research outputs found
Solution of the two impurity, two channel Kondo Model
We solve the two-impurity two-channel Kondo model using a combination of
conformal invariance and bosonisation techniques. The odd-even symmetric case
is analysed in detail. The RKKY interaction turns out to be exactly marginal,
resulting in a line of non-Fermi liquid fixed points. Explicit formulae are
given for the critical exponents and for the finite-size spectrum, which depend
continuously on a single parameter. The marginal line spans a range of values
of the RKKY coupling which goes from the infinitely strong ferromagnetic
point (associated with a 4-channel spin-1 Kondo model) to a finite
antiferromagnetic critical value beyond which a Fermi liquid is
recovered. We also find that, when the odd-even symmetry is broken, the
marginal line is unstable for ferromagnetic , while for antiferromagnetic
it extends into a manifold of fixed points.Comment: 9 pages, preprint LPTENS 94/1
Pedestrian Approach to the Two-Channel Kondo Model
We reformulate the two-channel Kondo model to explicitly remove the
unscattered charge degrees of freedom. This procedure permits us to move the
non-Fermi liquid fixed point to infinite coupling where we can apply a
perturbative strong-coupling expansion. The fixed point Hamiltonian involves a
three-body Majorana zero mode whose scattering effects give rise to marginal
self-energies. The compactified model is the N=3 member of a family of "O(N)"
Kondo models that can be solved by semiclassical methods in the large
limit. For odd , {\em fermionic} "Kink" fluctuations about the
mean-field theory generate a fermionic -body bound-state which
asymptotically decouples at low energies. For N=3, our semi-classical methods
fully recover the non-Fermi liquid physics of the original two channel model.
Using the same methods, we find that the corresponding O(3) Kondo lattice model
develops a spin-gap and a gapless band of coherently propagating three-body
bound-states. Its strong-coupling limit offers a rather interesting realization
of marginal Fermi liquid behavior.Comment: 17 pages, Revtex 3.0. Replaced with fully compiled postscript file