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Phys. Rev. Lett. 87, 277201 (2001) [4 pages]

Disorder Induced Cross-Over Effects at Quantum Critical Points

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Enrico Carlon1, Péter Lajkó2, and Ferenc Iglói3,2,4
1INFM, Dipartimento di Fisica, Universitá di Padova, I-35131 Padova, Italy
2Institute for Theoretical Physics, Szeged University, H-6720 Szeged, Hungary
3Research Institute for Solid State Physics and Optics, H-1525 Budapest, P.O. Box 49, Hungary
4Centre de Recherches sur les Très Basses Températures, B. P. 166, F-38042 Grenoble, France

Received 17 June 2001; revised 16 October 2001; published 12 December 2001

Critical properties of quantum spin chains with varying degrees of disorder are studied at zero temperature by analytical and extensive density matrix renormalization methods. Generally the phase diagram is found to contain three phases. The weak disorder regime, where the critical behavior is controlled by the fixed points of the pure system, and the strong disorder regime, which is attracted by an infinite randomness fixed point, are separated by an intermediate disorder regime, where dynamical scaling is anisotropic and the static and dynamical exponents are disorder dependent.

© 2001 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.87.277201
DOI:
10.1103/PhysRevLett.87.277201
PACS:
75.50.Lk, 05.30.-d, 75.10.Nr, 75.40.Gb