Dresden 2011 – wissenschaftliches Programm
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KR: Fachgruppe Kristallographie
KR 5: Poster Multiferroics (Joint Session of MA, DF, DS, KR, TT)
KR 5.57: Poster
Dienstag, 15. März 2011, 10:45–13:00, P2
Competing Ferri- and Antiferromagnetic Phases in Geometrical Frustrated LuFe2O4 — •Joost de Groot1, Karin Schmalzl1, Andrew Christianson2, Mark Lumsden2, Karol Marty2, Shilpa Adiga2, Stephen Nagler2, Werner Schweika1, Zahra Yamani3, and Manuel Angst1 — 1IFF, JARA-FIT, Forschungszentrum Jülich GmbH, Jülich, Germany — 2Oak Ridge National Laboratory, Oak Ridge, USA — 3Canadian Neutron Beam Center, Chalk River, Canada
LuFe2O4 is proposed to be a multiferroic material [1], with a novel mechanism for ferroelectricity, based on Fe2+/Fe3+ charge order (CO). Frustration leads to near degeneracy between ferro- and antiferroelectric CO, with antiferroelectric long range order established below TCO∼320K [2]. Clarifying the magnetic long range order below TN∼240K [3] and the transition to a glassy state at TLT∼170K is as important as elucidating the origin of (anti)ferroelectricity.
We will present a detailed study of the magnetic field - temperature phase diagram, which features an antiferromagnetic and a ferrimagnetic phase and for low temperatures a phase separation. We demonstrate that nearly degenerate ferrimagnetic and antiferromagnetic instabilities at TN are the key to the remarkably rich phase diagram. These bear a striking resemblance to nearly degenerate antiferro- and ferroelectric CO instabilities at TCO[2].
[1]N. Ikeda et al., Nature 436 1136 (2005); [2]M. Angst et al., Phys. Rev. Lett. 101 227601 (2008); [3]A. D. Christianson et al., Phys. Rev. Lett. 100 107601 (2008).