NUIM Math. Physics seminar

Claudio Castelnovo  
Oxford

Manifestations of monopole physics in spin ice materials

Friday 11 December 2009 at 2.00 p.m.

PCT (Physics and Chemistry Lecture Theatre) , Science Building, NUIM North Campus

Abstract:

Spin ice materials such as Dy2Ti2O7 and Ho2Ti2O7 provide a rare instance of fractionalisation in three dimensions: their elementary excitations at low temperature carry a fraction of the magnetic moment of the microscopic spin degrees of freedom, and they can be thought of as magnetic monopoles. The peculiar nature of these excitations leads to unique signatures in the equilibrium and response properties. These include unusual neutron scattering structure factors, dynamical arrest and long lived non-equilibrium metastable states, as well as a response to external magnetic fields that promotes spin ice as the magnetic analogue of an electrolyte. In this talk, we review several of these striking phenomena, and we show how they can be understood under the general theoretical framework of Coulomb liquids. The formulation of the low-temperature phase in terms of an emergent gauge field permits an unusual degree of analytical progress in modelling these materials.

All are welcome. Tea/coffee and biscuits to follow. For directions to the Dept. please check http://www.thphys.nuim.ie/map.php