Dresden 2014 – wissenschaftliches Programm
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KR: Fachgruppe Kristallographie
KR 4: Multiferroics I (MA jointly with DF, DS, KR, TT)
KR 4.10: Vortrag
Dienstag, 1. April 2014, 12:00–12:15, BEY 118
Thermodynamic properties of the new multiferroic material (NH4)2[FeCl5(H2O)] — •Matthias Ackermann1, Daniel Brüning2, Thomas Lorenz2, Petra Becker1, and Ladislav Bohatý1 — 1Institut für Kristallographie, Universität zu Köln, Germany — 2II. Physikalisches Institut, Universität zu Köln, Germany
Multiferroic materials with coupled ferroelectric and (anti-)ferromagnetic order in the same phase have attracted considerable interest during the last decade. The search for new multiferroic materials is an important issue to further improve the understanding of the underlying coupling mechanisms. Here, we present a detailed investigation of the new multiferroic compound (NH4)2[FeCl5(H2O)] [1]. Our measurements of pyroelectric currents reveal, that the electric polarization occuring in the antiferromagnetically ordered phase can drastically be influenced by applying magnetic fields. Based on the results of these dielectric investigations, together with measurements of thermal expansion, magnetostriction and specific heat, detailed magnetic field versus temperature phase diagrams are derived. Depending on the direction of the magnetic field up to three different multiferroic phases are identified, which are separated from the paramagnetic phase by a magnetically ordered, but non-ferroelectric phase.
This work was supported through the Institutional Strategy of the University of Cologne within the German Excellence Initiative.
Ackermann M et al. 2013 New J. Phys. (in press, arXiv:1308.0285)