Universität zu Köln

Schneider, Imke, Fritz, Lars, Anders, Frithjof B., Benlagra, Adel and Vojta, Matthias ORCID: 0000-0002-5740-831X (2011). Two-channel pseudogap Kondo and Anderson models: Quantum phase transitions and non-Fermi liquids. Phys. Rev. B, 84 (12). COLLEGE PK: AMER PHYSICAL SOC. ISSN 1098-0121

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Abstract

We discuss the two-channel Kondo problem with a pseudogap density of states rho(omega) proportional to vertical bar omega vertical bar(r) of the bath fermions. Combining both analytical and numerical renormalization group techniques, we characterize the impurity phases and quantum phase transitions of the relevant Kondo and Anderson models. The line of stable points, corresponding to the overscreened non-Fermi-liquid behavior of the metallic r = 0 case, is replaced by a stable particle-hole-symmetric intermediate-coupling fixed point for 0 < r < r(max) approximate to 0.23. For r > r(max), this non-Fermi-liquid phase disappears, and instead a critical fixed point with an emergent spin-channel symmetry appears, controlling the quantum phase transition between two phases with stable spin and channel moments, respectively. We propose low-energy field theories to describe the quantum phase transitions, all being formulated in fermionic variables. We employ epsilon expansion techniques to calculate critical properties near the critical dimensions r = 0 and 1, the latter being potentially relevant for two-channel Kondo impurities in neutral graphene. We find the analytical results to be in excellent agreement with those obtained from applying Wilson's numerical renormalization group technique.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Schneider, Imke UNSPECIFIED UNSPECIFIED UNSPECIFIED Fritz, Lars UNSPECIFIED UNSPECIFIED UNSPECIFIED Anders, Frithjof B. UNSPECIFIED UNSPECIFIED UNSPECIFIED Benlagra, Adel UNSPECIFIED UNSPECIFIED UNSPECIFIED Vojta, Matthias UNSPECIFIED orcid.org/0000-0002-5740-831X UNSPECIFIED
URN:	urn:nbn:de:hbz:38-488782
DOI:	10.1103/PhysRevB.84.125139
Journal or Publication Title:	Phys. Rev. B
Volume:	84
Number:	12
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 NUMERICAL-RENORMALIZATION-GROUP; MAGNETIC-IMPURITIES; GROUND-STATE; FIXED-POINTS; LARGE-N; SYSTEMS; SUPERCONDUCTORS; SUSCEPTIBILITY; DYNAMICS; METALS Multiple languages Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/48878