Berlin 2015 – wissenschaftliches Programm
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KR: Fachgruppe Kristallographie
KR 4: Multiferroics I (DF jointly with DS, KR, MA, TT)
KR 4.12: Vortrag
Mittwoch, 18. März 2015, 12:30–12:45, EB 107
Anisotropy study of multiferroicity in the pyroxene NaFeGe2O6 — •Lionel Andersen1, Thomas Lorenz1, Matthias Ackermann2, Ladislav Bohatý2, and Petra Becker2 — 1II. Physikalisches Institut - Universität zu Köln, Germany — 2Institut für Kristallographie - Universität zu Köln, Germany
Since the mineral aegirine was found to be the first multiferroic member of the pyroxenes an intensive search for further related multiferroics was initiated [1]. In this contribution, we present a detailed study of the dielectric, magnetic and magnetoelastic properties of the pyroxene NaFeGe2O6 with special respect to the anisotropy. Unlike other investigations on NaFeGe2O6 [2] large single crystals where synthesized to examine pyroelectric currents, dielectric constants and magnetic susceptibilities as well as the thermal expansion and the magnetostriction. The spontaneous electric polarization detected below TC≃11.6 K in an antiferromagnetically ordered state (TN≃13 K) is mainly lying within the ac plane with a small component along b, indicating a triclinic symmetry of the multiferroic phase of NaFeGe2O6. The electric polarization can be strongly modified by applying magnetic fields along different directions. We derive detailed magnetic-field versus temperature phase diagrams and identify three multiferroic low-temperature phases, which are separated by a non-ferroelectric, antiferromagnetically ordered state from the paramagnetic high-temperature phase [3].
[1] S. Jodlauk et al. J. Phys.: Condens. Matter 19 (2007)
[2] I. Kim et al. J. Phys.: Condens. Matter 24 (2012)
[3] M. Ackermann et al. New J. Phys. (submitted, arXiv:1408.6772)