Thursday's seminar

[Cond.Matt. & Stat.Mech.Section]

SEMINAR on Disorder and strong electron correlations

 

 

Thursday, 4 November   -  11:30 a.m.

  

Luigi Stasi Seminar Room,  Leonardo Building - first floor

 

 

Alexei ANDREANOV    ( ICTP, Trieste  )

 

"Quantum spin glass: A journey to T=0"

 

Abstract

 

Shortly after the introduction of the Sherrington-Kirkpatrick (SK) model for spin glasses (SG) its quantum generalisation was considered by Bray and Moore (1980). They established the survival of the SG phase under quantum fluctuations. Further studies refined their results for the location of the quantum phase transition (QPT), as well as the behaviour of the system in its vicinity. However, the bulk of the works focused on the paramagnetic phase, the low-T region remaining a puzzle. We filled this gap by studying the transverse field SK model at T=0. Among the key properties observed/confirmed are the gapless nature of the low-T phase and the presence of the specific low-energy excitations (both related to the marginal stability of the phase), as well as the existence of a fixed point in the solution of the Parisi equations which describe the low-T solution.

 

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).