Regensburg 2013 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 7: Correlated Electrons: Spin Systems, Itinerant Magnets 1
TT 7.12: Vortrag
Montag, 11. März 2013, 12:30–12:45, H19
Anormalous dynamics of electric dipoles on magnetic monopoles in spin ice — •Christoph Grams, Martin Valldor, and Joachim Hemberger — II. Physikalisches Institut, Universität zu Köln, Cologne, Germany
The coupling of electric dipoles to magnetic monopoles [1] enables us to see magnetic monopoles with dielectric spectroscopy. Therefore we can use our setup in the dilution cryostat to evaluate monopole dynamics in Dy2Ti2O7 in a frequency range up to 1 MHz with magnetic and electric field parallel to the [111] direction of the sample down to 100 mK.
Our measurements show an anomaly in the monopole dynamics in a conic area in the (H,T) phase diagram above the critical endpoint (approximately 400 mK and 1 T) of the first order monopole liquid-gas transition [2]. Repeating the measurements with the electric field perpendicular to the magnetic field the abnormal dynamics vanish, indicating an anisotropy of the polarization and thereby promoting the idea of antiferroelectric order in the high field phase.
Work supported by the DFG through SFB 608.
[1] D. I. Khomskii, Nature Commun. 3, 1-13 (2012)
C. Castelnovo et al., Nature 451(7174), 42-5 (2008)