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Titolo:
Generalized antiferromagnetic Heisenberg spin ladders
Autore:
Tsai, YC; Hu, CK;
Indirizzi:
Natl Chung Cheng Univ, Dept Phys, Chiayi, Taiwan Natl Chung Cheng Univ Chiayi Taiwan eng Univ, Dept Phys, Chiayi, Taiwan Acad Sinica, Inst Phys, Taipei, Taiwan Acad Sinica Taipei TaiwanAcad Sinica, Inst Phys, Taipei, Taiwan
Titolo Testata:
PHYSICA B
fascicolo: 1, volume: 305, anno: 2001,
pagine: 21 - 37
SICI:
0921-4526(200110)305:1<21:GAHSL>2.0.ZU;2-8
Fonte:
ISI
Lingua:
ENG
Soggetto:
NONLINEAR-SIGMA-MODEL; NEUTRON-SCATTERING; LOW-TEMPERATURES; 2-LEG LADDERS; 1/S EXPANSION; 2 DIMENSIONS; MONTE-CARLO; S=1/2; FERROMAGNETS; SR2CUO2CL2;
Keywords:
antiferromagnets; spin ladders;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
39
Recensione:
Indirizzi per estratti:
Indirizzo: Tsai, YC Natl Chung Cheng Univ, Dept Phys, Chiayi, Taiwan Natl Chung ChengUniv Chiayi Taiwan Dept Phys, Chiayi, Taiwan
Citazione:
Y.C. Tsai e C.K. Hu, "Generalized antiferromagnetic Heisenberg spin ladders", PHYSICA B, 305(1), 2001, pp. 21-37

Abstract

We utilize the path-integral technique to derive the non-linear Sigma model (NL sigmaM) for generalized antiferromagnetic spin-ladder systems on the square lattice with diagonal (next-nearest neighbor) interactions in addition to the nearest neighbor interaction. The model Hamiltonian is: H = Sigma(n)(a=1)' Sigma (1) J(a)S(a(i))(. )S(a)(i+1) + J ' S-a,a+1(a)(i)S-.(a+1)(i)+ K(a,a+1)Sa(i) (. ) Sa+1(i+1) + Ma,a+1Sa(i+1) (. ) S-a(i+1) (. ) S-a(i). Thetopological term of the NL sigmaM is absent for the spin-s ladder with an even number of legs and is equal to 2 pis for the ladder with an odd numberof legs. The spin wave velocity is s[Sigma (a)(J(a) - M-a,M-a+1 - K-a,K-a+1)/Sigma L-b,c(b,c)-1](1/2) where L-a,L-b = 4J(a) + J ' (a,a+1) + J ' (a-1)- M-a,M-a+1- M-a,M-a-1-K-a,K-a+1-K-a,K-a-1 when a = b, and L-a,L-b = J ' (a,b) + K-a,K-b + M-a,M-b, when /a - b/ = 1. The spin gaps are predicted forspin ladders with an even number of chains. We also consider a two-leg ladder with spin (s) over tilde and s, in which diagonal interactions occur only in the even (or odd) cells. The Berry phase is found to be dependent on the coupling constants. The expressions of the spin-wave velocity and spin gap are also given for even-leg ladders. The operator approach to the generalized spin-ladder problem is also presented. Finally we address the finite-size NL sigmaM treatment of this system. (C) 2001 Elsevier Science B.V. All rights reserved.

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Documento generato il 01/04/20 alle ore 01:08:36