Thursday's seminar

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

SEMINAR on  Disorder and strong electron correlations





Thursday, 19 November      -  11:00 a.m.





Seminar Room,  Leonardo Building - first floor





Roderich MOESSNER     ( Max Planck Institute for the Physics of  
Complex Systems, Dresden )



"Magnetic monopoles in spin ice"



Abstract



Electrically charged particles, such as the electron, are ubiquitous.   
By contrast, no elementary particles with a net magnetic charge have  
ever been observed, despite intensive and prolonged searches.

An alternative strategy is to realise them not as elementary but  
rather as emergent particles, i.e., as manifestations of the  
correlations present in a strongly interacting many-body system.   
Indeed, it turns out  that magnetic monopoles do emerge in a class of  
exotic magnets known collectively as spin ice: the dipole moment of  
the underlying electronic degrees of freedom fractionalises into  
monopoles!  These monopoles can in principle be detected in an  
experiment modelled after the celebrated Stanford search for magnetic  
monopoles of cosmic origin.  The many-body state of spin ice, in turn,  
represents a  new type of  phase outside the standard classification  
of magnetic order and disorder.

  Reference: C. Castelnovo, R. Moessner and S. L. Sondhi, Nature 451,  
42 (2008).