Universität zu Köln

Chowdhury, Tathagata, Rosch, Achim ORCID: 0000-0002-6586-5721 and Bulla, Ralf (2020). Competition between Kondo physics and Kitaev physics in Kitaev clusters coupled to a fermionic bath. Phys. Rev. B, 101 (11). COLLEGE PK: AMER PHYSICAL SOC. ISSN 2469-9969

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Abstract

Geometrically frustrated quantum impurities coupled to metallic leads have been shown to exhibit rich behavior with a quantum phase transition separating Kondo screened and local moment phases. Frustration in the quantum impurity can alternatively be introduced via Kitaev couplings between different spins of the impurity cluster. We use the numerical renormalization group (NRG) to study a range of systems where the quantum impurity comprising a Kitaev cluster is coupled to a bath of noninteracting fermions. The models exhibit a competition between Kitaev and Kondo dominated physics depending on whether the Kitaev couplings are greater or less than the Kondo temperature. We characterize the ground-state properties of the system and determine the temperature dependence of the crossover scale for the emergence of fractionalized degrees of freedom in the model. We also demonstrate qualitatively as well as quantitatively that in the Kondo limit, the complex impurity can be mapped to an effective two-impurity system, where the emergent spin 1/2 comprises of both Majorana and flux degrees of freedom. For a tetrahedral-shaped Kitaev cluster, an extra orbital degree of freedom closely related to a flux degree of freedom remains unscreened even in the presence of both Heisenberg and Kondo interactions.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Chowdhury, Tathagata UNSPECIFIED UNSPECIFIED UNSPECIFIED Rosch, Achim UNSPECIFIED orcid.org/0000-0002-6586-5721 UNSPECIFIED Bulla, Ralf UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-340645
DOI:	10.1103/PhysRevB.101.115133
Journal or Publication Title:	Phys. Rev. B
Volume:	101
Number:	11
Date:	2020
Publisher:	AMER PHYSICAL SOC
Place of Publication:	COLLEGE PK
ISSN:	2469-9969
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Physics > Institute for Theoretical Physics
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language RENORMALIZATION-GROUP Multiple languages Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/34064