%0 Journal Article
%A Brüning, Daniel
%A Fröhlich, Tobias
%A Langenbach, Malte
%A Leich, Thomas
%A Meven, Martin
%A Becker, Petra
%A Bohatý, Ladislav
%A Grüninger, Markus
%A Braden, Markus
%A Lorenz, Thomas
%T Magnetoelectric coupling in the mixed erythrosiderite [(NH$_4$)$_{1−x}$K$_x$]$_2$[FeCl$_5$(H$_2$O)]
%J Physical review / B
%V 102
%N 5
%@ 2469-9950
%C Woodbury, NY
%I Inst.
%M FZJ-2020-04850
%P 054413
%D 2020
%X We present a study of the dielectric, structural and magnetic properties of the multiferroic orlinear magnetoelectric substitution series [(NH4)1􀀀xKx]2[FeCl5(H2O)]. Pyroelectric currents, magneticsusceptibilities, and thermodynamic properties were examined on large single crystals of theerythrosiderite compounds and detailed magnetic-eld versus temperature phase diagrams are derivedfor three dierent substitution levels. With increasing potassium concentration the material istuned from a multiferroic (x  0:06) to a linear magnetoelectric (x  0:15) ground state. In contrastto the respective pure parent compounds with x = 0 or 1, however, the ferroelectric or linear magnetoelectricpolarization in none of the substituted samples is switchable by external electric elds,because these samples exhibit a signicant electric polarization already above the magnetic orderingtransition. The polarization arises at a higher-lying structural phase transition that is examined byTHz spectroscopy and by comprehensive neutron-diraction experiments on a deuterated pure singlecrystal. The structural phase transition is attributed to an ordering of NH+4 tetrahedra but doesnot break inversion symmetry in the pure material, while nite K content causes pyroelectricity.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000557288200001
%R 10.1103/PhysRevB.102.054413
%U https://juser.fz-juelich.de/record/888331