We demonstrate that ethylammonium copper chloride, ͑C 2 H 5 NH 3 ͒ 2 CuCl 4 , a member of the hybrid perovskite family is an electrically polar and magnetic compound with dielectric anomaly around the Curie point ͑247 K͒. We have found large spontaneous electric polarization below this point accompanied with a color change in the sample. The system is also ferroelectric, with large remnant polarization ͑37 C / cm 2 ͒ that is comparable to classical ferroelectric compounds. The results are ascribed to hydrogen-bond ordering of the organic chains. The coexistence of ferroelectricity and dominant ferromagnetic interactions allows to relate the sample to a rare group of magnetic multiferroic compounds. In such hybrid perovskites the underlying hydrogen bonding of easily tunable organic building blocks in combination with the 3d transition-metal layers offers an emerging pathway to engineer multifuctional multiferroics. Vigorous research efforts on magnetoelectric effects in the recent years 1-3 has stimulated the exploratory design and synthesis of magnetoelectric materials 4 and reinvestigation of known compounds, where BiFeO 3 stands out as a prominent example. 5 Single phase materials where magnetism and ferroelectricity ͑FE͒ coexist are rare. This is basically due to the mutual exclusive requirement for closed-shell cations for the former and unpaired spins on the same lattice site for the latter mechanism to be operative. Broadly speaking there are two families 6 of multiferroics ͑i͒ materials where electric polarization and magnetism have different origins and consequently different ordering temperatures due to the different functional subsystems and ͑ii͒ materials where the polar state takes place only when the specific ͑antiferro͒magnetically ordered state is established. In the latter case, the spin driven microscopic mechanisms 7,8 ͑including spontaneous magnetostriction 9,10 ͒ can produce the loss of inversion symmetry at the spin reorientation transition and give rise to an electrically polar state.Although the strongest magnetoelectric interactions are expected between ferromagnetic ͑FM͒ and ferroelectric subsystems the majority of the investigated magnetoelectric materials today are antiferromagnetic ͑AFM͒. In that respect identifying a ferroelectric ferromagnet or magnetic material, with dominant ferromagnetic interactions, as reported here, is indeed a demanding task for the modern solid-state materials physics. The early discovery of the weakly ferromagnetic ͑T c =60 K͒ but also electrically polarizable nickelboracite Ni 3 B 7 O 13 I system, 11 where the three-dimensionally linked metal-halogen-metal chains can support not only collective magnetic phenomena but also their interaction with electric polarization, has not been followed yet by other similar successes. The aforementioned compound belongs to a not so well exploited class of materials involving functional building groups, with strong dielectric response, embedded though in a sublattice of magnetic cations; this conceptually results into tw...
Despite symmetrical polarization, the magnitude of a light-induced voltage is known to be asymmetric with respect to poling sign in many photovoltaic (PV) ferroelectrics (FEs). This asymmetry remains unclear and is often attributed to extrinsic effects. We show here for the first time that such an asymmetry can be intrinsic, steaming from the superposition of asymmetries of internal FE bias and electro-piezo-strictive deformation. This hypothesis is confirmed by the observed decrease of PV asymmetry for smaller FE bias. Moreover, the both PV effect and remanent polarization are found to increase under vacuum-induced expansion and to decrease for gas-induced compression, with tens percents tunability. The change in cations positions under pressure is analysed through the first-principle density functional theory calculations. The reported properties provide key insight for FE-based solar elements optimization.
The recently reported ability to induce and tune a sign of the magnetoelectric (ME) interactions in NH2(CH3)2Al1−xCrx(SO4)2 · 6H2O crystals as a function of Cr content is further investigated here. The ME coupling and its larger absolute value for the sample with larger Cr content agrees qualitatively with thermodynamic Landau analysis. However, quantitative estimation implies other contributions as well. The observed nontrivial magnetic field dependence of ferroelectric transition can be explained within the model that takes into account influence of the arising local deformation of the lattice on the two types of DMA group responsible respectively for the ferroelectric and antiferroelectric ordering.
This paper presents the results of investigations of the temperature dependence of heat capacity and dielectric dispersion in the vicinity of ferroelectric-ferroelastic phase transition of dimethylammonium metal sulphate hexahydrate crystals DMAAl1−xCrxS. In particular, it is shown that the isomorphous substitution of metal ion noticeably changes the temperature of phase transition and parameters of the fundamental ferroelectric dispersion observed around Tc1. These changes are explained in terms of clusters sizes and dynamics in the framework of order-disorder type phase transition mechanism.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.