Berlin 2012 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 14: Matter At Low Temperature: Multiferroics (jointly with MA, DF, DS, KR
TT 14.1: Invited Talk
Monday, March 26, 2012, 16:45–17:15, H 3005
Multiferroicity in an organic charge-transfer salt: Electric-dipole-driven magnetism — •Peter Lunkenheimer1, Jens Müller2, Stephan Krohns1, Florian Schrettle1, Alois Loidl1, and Michael Lang2 — 1Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, Germany — 2Institute of Physics, Goethe-University Frankfurt, Germany
Multiferroics, showing simultaneous electrical and magnetic ordering, are remarkable materials from both an academic and technological point of view. A prominent mechanism is the spin-driven ferroelectricity, often found in materials with helical spin order. However, recently a different mechanism, namely purely electronic ferroelectricity, where charge order breaks inversion symmetry, has attracted considerable interest. In the present talk, I will treat examples for both types of multiferroics like perovskite manganites and magnetite, concentrating on their dielectric properties, which often are only poorly characterized. An especially interesting case is a two-dimensional organic charge-transfer salt, which shows ferroelectricity, accompanied by antiferromagnetic spin order and belongs to a new class of multiferroics [1]. In this material, the ferroelectric ordering leads to a breaking of spin frustration, which triggers simultaneous dipolar and spin order. Hence, here the spin order is driven by the ferroelectricity, in marked contrast to the spin-driven ferroelectricity in helical magnets.
P. Lunkenheimer, J. Müller, S. Krohns, F. Schrettle, A. Loidl, B. Hartmann, R. Rommel, M. de Souza, C. Hotta, J.A. Schlueter, M. Lang, preprint (arXiv:1111.2752).