Europhys. Lett.
Volume 61, Number 6, March 2003
Page(s) 831 - 837
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 01 March 2003
DOI: 10.1209/epl/i2003-00309-6
Europhys. Lett., 61 (6) , pp. 831-837 (2003)

Griffiths phases in the strongly disordered Kondo necklace model

T. G. Rappoport1, A. Saguia2, B. Boechat1 and M. A. Continentino1

1  Departamento de Física, Universidade Federal Fluminense Av. Litorânea s/n, Niterói, 24210-340, RJ, Brazil
2  Centro Brasileiro de Pesquisas Físicas - Rua Dr. Xavier Sigaud 150 Urca, Rio de Janeiro, 22290-180, RJ, Brazil

(Received 31 July 2002; accepted in final form 14 January 2003)

The effect of strong disorder on the one-dimensional Kondo necklace model is studied using a perturbative real-space renormalization group approach which becomes asymptotically exact in the low-energy limit. The phase diagram of the model presents a random quantum critical point separating two phases; a random XY-like phase similar to a quantum disordered XY chain and the random Kondo phase. We also consider an anisotropic version of the model which for strong disorder maps on the random transverse field Ising model.

75.10.Hk - Classical spin models.
64.60.Ak - Renormalization-group, fractal, and percolation studies of phase transitions.
64.60.Cn - Order-disorder transformations; statistical mechanics of model systems.

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