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Mitchell, Andrew K. and Bulla, Ralf (2015). Validity of the local self-energy approximation: Application to coupled quantum impurities. Phys. Rev. B, 92 (15). COLLEGE PK: AMER PHYSICAL SOC. ISSN 1550-235X

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Abstract

We examine the quality of the local self-energy approximation, applied here to models of multiple quantum impurities coupled to an electronic bath. The local self-energy is obtained by solving a single-impurity Anderson model in an effective medium that is determined self-consistently, similar to the dynamical mean-field theory (DMFT) for correlated lattice systems. By comparing to exact results obtained by using the numerical renormalization group, we determine situations where impurity-DMFT is able to capture the physics of highly inhomogeneous systems and those cases where it fails. For two magnetic impurities separated in real space, the onset of the dilute limit is captured, but RKKY-dominated interimpurity singlet formation cannot be described. For parallel quantum dot devices, impurity-DMFT succeeds in capturing the underscreened Kondo physics by self-consistent generation of a critical pseudogapped effective medium. However, the quantum phase transition between high- and low-spin states upon tuning interdot coupling cannot be described.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Mitchell, Andrew K. UNSPECIFIED UNSPECIFIED UNSPECIFIED Bulla, Ralf UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-391587
DOI:	10.1103/PhysRevB.92.155101
Journal or Publication Title:	Phys. Rev. B
Volume:	92
Number:	15
Date:	2015
Publisher:	AMER PHYSICAL SOC
Place of Publication:	COLLEGE PK
ISSN:	1550-235X
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 MEAN-FIELD THEORY; RENORMALIZATION-GROUP; ANDERSON MODEL; ELECTRONIC-STRUCTURE; SYSTEMS; DOTS; DIMENSIONS; TRANSITION; SURFACE; METAL Multiple languages Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/39158