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Résumé |
Quantum spin glasses are glassy systems where both thermal and quantum
fluctuations can drive the transition. The generic interest to these systems
is motivated by a question "How quantum fluctuations affect the glass phase:
can they destroy it ? How do they affect its properties ?"
We have studied a transverse field Ising spin glass [2,3] where the strength
of quantum fluctuations is tuned by a transverse field. The model
possesses a paramagnetic
and a glass phases [2,3]. The presence of the quantum phase transition is well
established however little is known about the nature of the glass
phase. We have proved that
the entire glass phase is critical and gapless giving rise to specific low
lying excitations which can be interpreted as an Ohmic bath of oscillators.
For small transverse fields we have also discovered a fixed point of the Parisi
equations identical to that uncovered by Pankov in classical spin glasses[3].
Refs:
1. A. Bray and M. Moore, J. Phys. C 13, L655 (1980).
2. J. Miller and D. Huse, PRL 70, 20 (1993) 3147.
3. M.J. Rozenberg and D.R. Grempel, PRL 81, 12 (1998) 2550.
4. S. Pankov, PRL 96, 197204 (2006).
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