A holographic model of the Kondo effect

Duration: 44 mins 55 secs

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Description:	Erdmenger, JK (Max-Planck-Institut für Physik, München) Friday 20 September 2013, 14:00-14:45


Created:	2013-09-24 17:01
Collection:	Mathematics and Physics of the Holographic Principle
Publisher:	Isaac Newton Institute
Copyright:	Erdmenger, JK
Language:	eng (English)


Abstract:	Coauthors: C. Hoyos (Tel Aviv Univ.), A. O'Bannon (DAMTP Cambridge), J. Wu (NCTS Taiwan) We propose a holographic model of the Kondo effect, i.e. of the screening of a magnetic impurity coupled to a bath of conduction electrons at low temperatures. In a (1+1)-dimensional CFT description, this corresponds to an RG flow from an UV to an IR fixed point triggered by a marginally relevant (0+1)-dimensional operator. In the large N limit, with spin SU(N) and charge U(1) symmetries, the Kondo effect appears as a mean-field phase transition in which the U(1) symmetry is spontaneously broken. Inspired by a top-down brane model, we model the Kondo RG flow by an AdS_3 Chern-Simons action coupled to an AdS_2 holographic superconductor. We observe several characteristic features of the Kondo effect in this model, such as dynamical scale generation and a phase shift. Moreover, we find a power-law behaviour of the resistivity with temperature which is consistent with over-screening. Our model may serve as a basis for investigating more involved problems such as Kondo lattices.

Abstract:

Coauthors: C. Hoyos (Tel Aviv Univ.), A. O'Bannon (DAMTP Cambridge), J. Wu (NCTS Taiwan)

We propose a holographic model of the Kondo effect, i.e. of the screening of a magnetic impurity coupled to a bath of conduction electrons at low temperatures. In a (1+1)-dimensional CFT description, this corresponds to an RG flow from an UV to an IR fixed point triggered by a marginally relevant (0+1)-dimensional operator. In the large N limit, with spin SU(N) and charge U(1) symmetries, the Kondo effect appears as a mean-field phase transition in which the U(1) symmetry is spontaneously broken. Inspired by a top-down brane model, we model the Kondo RG flow by an AdS_3 Chern-Simons action coupled to an AdS_2 holographic superconductor. We observe several characteristic features of the Kondo effect in this model, such as dynamical scale generation and a phase shift. Moreover, we find a power-law behaviour of the resistivity with temperature which is consistent with over-screening. Our model may serve as a basis for investigating more involved problems such as Kondo lattices.

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