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arXiv · 1707.01387

Manumitting slave-spins in the Anderson impurity model

Daniele Guerci·Michele Fabrizio
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Abstract

We show that a generic single-orbital Anderson impurity model, lacking for instance any kind of particle-hole symmetry, can be exactly mapped without any constraint onto a resonant level model coupled to two Ising variables, which reduce to one if the hybridisation is particle-hole symmetric. The mean-field solution of this model is found to be stable to unphysical spontaneous magnetisation of the impurity, unlike the saddle-point solution in the standard slave-boson representation. Remarkably, the mean-field estimate of the Wilson ratio approaches the exact value $R_\text{W}=2$ in the Kondo regime.

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Daniele Guerci, Michele Fabrizio. 2017-10-30. Manumitting slave-spins in the Anderson impurity model. https://doi.org/10.1103/physrevb.96.201106

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