Dresden 2014 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 8: Correlated Electrons: Spin Systems and Itinerant Magnets - Frustrated Magnets I
TT 8.1: Vortrag
Montag, 31. März 2014, 09:30–09:45, HSZ 304
Critical speeding-up near the monopole liquid-gas transition in magnetoelectric spin-ice — •Christoph P. Grams1, Martin Valldor1,2, Markus Garst3, and Joachim Hemberger1 — 1II. Physikalisches Institut, Universität zu Köln, Cologne, Germany — 2Max Planck Institute for Chemical Physics of Solids, Dresden, Germany — 3Institut für Theoretische Physik, Universität zu Köln, Cologne, Germany
Competing interactions in the so-called spin-ice compounds stabilize a frustrated ground-state with finite zero-point entropy and, interestingly, emergent magnetic monopole excitations[1]. The properties of these monopoles are at the focus of recent research with particular emphasis on their quantum dynamics. It is predicted[2] that each monopole also possesses an electric dipole moment, which allows to investigate their dynamics via the dielectric function ε(ν).
In this talk I report on broadband spectroscopic measurements of ε(ν) in Dy2Ti2O7 down to temperatures of 200 mK with a specific focus on the critical endpoint present for a magnetic field along the crystallographic [111] direction[3].
Funded through the Institutional Strategy of the University of Cologne within the German Excellence Initiative and research grant HE-3219/2-1.
C. Castelnovo et al., Nature 451 (2008) 42
D. I. Khomskii, Nature Comm. 3 (2012) 1
C. P. Grams et al., arXiv:1307.8287