Universität zu Köln

Mitchell, Andrew K., Becker, Michael and Bulla, Ralf (2011). Real-space renormalization group flow in quantum impurity systems: Local moment formation and the Kondo screening cloud. Phys. Rev. B, 84 (11). COLLEGE PK: AMER PHYSICAL SOC. ISSN 1098-0121

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Abstract

The existence of a length scale xi(K) similar to 1/T(K) (with T(K) the Kondo temperature) has long been predicted in quantum impurity systems. At low temperatures T << T(K), the standard interpretation is that a spin-1/2 impurity is screened by a surrounding Kondo cloud of spatial extent xi(K). We argue that renormalization group (RG) flow between any two fixed points (FPs) results in a characteristic length scale, observed in real space as a crossover between physical behavior typical of each FP. In the simplest example of the Anderson impurity model, three FPs arise, and we show that free orbital, local moment, and strong coupling regions of space can be identified at zero temperature. These regions are separated by two crossover length scales xi(LM) and xi(K), with the latter diverging as the Kondo effect is destroyed on increasing temperature through T(K). One implication is that moment formation occurs inside the Kondo cloud, while the screening process itself occurs on flowing to the strong coupling FP at distances similar to xi(K). Generic aspects of the real-space physics are exemplified by the two-channel Kondo model, where xi(K) now separates local moment and overscreening clouds.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Mitchell, Andrew K. UNSPECIFIED UNSPECIFIED UNSPECIFIED Becker, Michael UNSPECIFIED UNSPECIFIED UNSPECIFIED Bulla, Ralf UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-488979
DOI:	10.1103/PhysRevB.84.115120
Journal or Publication Title:	Phys. Rev. B
Volume:	84
Number:	11
Date:	2011
Publisher:	AMER PHYSICAL SOC
Place of Publication:	COLLEGE PK
ISSN:	1098-0121
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language MAGNETIC IMPURITY; METALS Multiple languages Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/48897