Thursday's seminar

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

SEMINAR on   Disorder and strong electron correlations





Thursday, 25 February      -  11:00 a.m.





EULER LECTURE HALL,  Leonardo Building - terrace level





Markus MÜLLER     ( I.C.T.P. )



"Criticality, shocks and avalanches in   spin glasses"



Abstract



The low temperature phase of spin glasses exhibits algebraically  
decaying spin-spin correlations at all T<Tc. This permanent  
criticality is an important hallmark of many glassy systems. It is  
closely related to the existence of a soft gap in the distribution of  
the local magnetic field and implies the presence of collective low  
energy excitations.  At T=0, when the magnetization is traced as a  
function of external field H, field-induced spin flips can trigger an  
avalanche of further spin flips. Here, criticality is non-trivially  
encoded in the power law distribution of the size of such events.  I  
will present an analytical theory for this phenomenon in the case of  
the SK spin glass, and discuss analogies with other glassy systems  
such as pinned elastic systems and electron glasses.