Phase diagram of an impurity in the spin-1/2 chain: Two-channel Kondo effect versus Curie law

Citation
S. Eggert et al., Phase diagram of an impurity in the spin-1/2 chain: Two-channel Kondo effect versus Curie law, PHYS REV L, 86(3), 2001, pp. 516-519
Citations number
26
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physics
Journal title
PHYSICAL REVIEW LETTERS
ISSN journal
0031-9007 → ACNP
Volume
86
Issue
3
Year of publication
2001
Pages
516 - 519
Database
ISI
SICI code
0031-9007(20010115)86:3<516:PDOAII>2.0.ZU;2-N
Abstract
We consider a magnetic S = 1/2 impurity in the antiferromagnetic spin chain as a function of two coupling parameters: the symmetric coupling of the im purity to two sites in the chain J(1) and the coupling between the two site s J(2). By using field theory arguments and numerical calculations we can i dentify all possible fixed points and classify the renormalization flow bet ween them, which leads to a nontrivial phase diagram. Depending on the deta iled choice of the two (frustrating) coupling strengths, the stable phases correspond either to a decoupled spin with Curie law behavior or to a non-F ermi-liquid fixed point with a logarithmically diverging impurity susceptib ility as in the two-channel Kondo effect. Our results resolve a controversy about the renormalization flow.