Abstract
We extend the Schwinger boson large treatment of the underscreened Kondo model in a way that correctly captures the finite elastic phase shift in the singular Fermi liquid. The new feature of the approach is the introduction of a flavor quantum number with possible values associated with the Schwinger boson representation. The large limit is taken maintaining the ratio fixed. This approach differs from previous approaches in that we do not explicitly enforce a constraint on the spin representation of the Schwinger bosons. Instead, the energetics of the Kondo model cause the bosonic degrees of freedom to “self-assemble” into a ground-state in which the spins of bosons and conduction electrons are antisymmetrically arranged into a Kondo singlet. With this device the large limit can be taken in such a way that a fraction of the Abrikosov-Suhl resonance is immersed inside the Fermi sea. We show how this method can be used to model the full energy dependence of the singular Abrikosov-Suhl resonance in the under-screened Kondo model and the field-dependent magnetization.
4 More- Received 14 June 2004
DOI:https://doi.org/10.1103/PhysRevB.71.035111
©2005 American Physical Society