Berlin 2012 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 14: Matter At Low Temperature: Multiferroics (jointly with MA, DF, DS, KR
TT 14.2: Vortrag
Montag, 26. März 2012, 17:15–17:30, H 3005
Critical dynamics in LiCuVO4 — •Christoph Grams1, Maximilian Schalenbach1, Daniel Niermann1, Sandra Niesen1, Petra Becker2, and Joachim Hemberger1 — 1II. Physikalisches Institut, Universität zu Köln, Germany — 2Institut für Kristallographie, Universität zu Köln, Germany
Without an external magnetic field LiCuVO4 has a phase transition into a cycloidal spin ordered phase below 2.3 K where it simultaneously is antiferromagnetic and ferroelectric. The transition temperature of this phase transition can be lowered with increasing magnetic field.
Ferroelectric phase transitions are of continuous fashion and are accompanied with a symmetry lowering that yields soft modes. Near the critical point the dynamics of the ionic polarization mechanisms are slowed down and therefore denoted as critical (“critical slowing down”).
We observe the critical dynamics of the low temperature multiferroic phase transition of LiCuVO4 with broadband dielectric spectroscopy. Therefore the compound’s dielectric response to an external electric AC field of frequencies from 10 mHz to several GHz in the temperature range 20 mK to 300 K was measured in dependence of magnetic fields up to 14 T.
Work supported by the DFG through SFB 608.