Berlin 2015 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 18: Correlated Electrons: Spin Systems and Itinerant Magnets – Frustrated Magnets 2 (jointly with MA)
TT 18.6: Vortrag
Montag, 16. März 2015, 16:15–16:30, H 3005
Magnetic monopoles in diluted quantum spin ice — •Olga Petrova1, Roderich Moessner1, and Shivaji Sondhi2 — 1Max Planck Institute for the Physics of Complex Systems, Dresden, Germany — 2Princeton University, Princeton, NJ, USA
Typical spin ice materials can be modeled using classical Ising spins. The geometric frustration of the pyrochlore lattice causes the spins to satisfy ice rules, whereas a violation of the ice constraint constitutes an excitation. Flipping adjacent spins fractionalizes the excitation into two monopoles. Long range dipolar spin couplings result in Coulombic interactions between charges, while the leading effect of quantum fluctuations is to provide the monopoles with kinetic energy. We study weakly diluted spin ice including the leading effects of quantum mechanical fluctuations. We find that a missing spin gives rise to hydrogenic excited states in which a magnetic monopole is bound to the vacancy at various radii. We compute the properties of these states via a mapping to a single particle problem that is defined on the Bethe lattice. These quantities are then used to obtain an expression for the dynamic structure factor, that can be measured in neutron scattering experiments directly.