Regensburg 2013 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 40: Poster Session Correlated Electrons
TT 40.65: Poster
Mittwoch, 13. März 2013, 15:00–19:00, Poster D
Preparation and characterization of doped spin ice — •Peter Laschitzky, Martin Hiertz, Oliver Breunig, Gerhard Kolland, Johanna Frielingsdorf, Martin Valldor, and Thomas Lorenz — II. Physikalisches Institut, Universität zu Köln
The magnetic Dy sites in Dy2Ti2O7 form a pyrochlore lattice consisting of corner-sharing tetrahedra. A strong crystal field results in an Ising anisotropy of the magnetic moments of the Dy site which align along their local easy axes in the {111} directions pointing either into or out of the tetrahedra. As a consequence, the spin system is geometrically frustrated even in the groundstate. The magnetic excitations in spin ice are discussed as magnetic monopoles. We synthesized the mother compound Dy2Ti2O7 and the doped compounds Dy2−xYxTi2O7 with x=0.1,0.2,1,2 and Dy2Ti1.8Zr0.2O7. Large, high-quality single crystals were grown by the floating-zone method. To characterize the grown crystals, we measured the magnetization, the specific heat and the thermal conductivity for various magnetic-field directions. Doping with non-magnetic Y has a strong influence on the magnetic subsystem. For example, the magnetic contribution κmag to the thermal conductivity1 can be completly suppressed by Y doping. Substitution of the non-magnetic Ti by larger Zr ions reduces the phononic thermal conductivity, whereas the magnetic contribution is essentially conserved.
Supported by the DFG through SFB 608
[1] Kolland et. al., Phys. Rev. B 86, 060402 (2012)