High Magnetic Hardness for the Canted Antiferromagnetic, Ferroelectric, and Ferroelastic Layered Perovskite-like (C₂H₅NH₃)₂[Fe^IICl₄]

Abstract

An unusual high magnetic hardness for the layered perovskite-like (C2H5NH3)2[Fe(II)Cl4], in addition to its already found canted antiferromagnetism, ferroelasticity, and ferroelectricity, which are absent for (CH3NH3)2[Fe(II)Cl4], has been observed. The additional CH2 in the ethylammonium compared to methylammonium allows more degrees of freedom and therefore numerous phase transitions which have been characterized by single-crystal structure determinations from 383 to 10 K giving the sequence from tetragonal to orthorhombic to monoclinic (I4/mmm ↔ P42/ncm ↔ Pccn ↔ Pcab ↔ C2/c) accompanied by both tilting and rotation of the FeCl6 octahedra. The magnetic properties on single crystal and powder samples at high temperature are similar for both compounds, but at TN (C2H5NH3)2[Fe(II)Cl4] is a proper canted antiferromagnet unlike the hidden canting observed for (CH3NH3)2[Fe(II)Cl4]. The canting angle is 0.6° toward the c-axis, and thus the moments lie in the easy plane of the iron-chloride layer defined by a critical exponent β = 0.18. The isothermal magnetizations for the field along the three orthogonal crystallographic axes show wider hysteresis for H ∥ c and is present at all temperature below 98 K. The coercive field increases as the temperature is lowered, and at T < 20 K it is difficult to reverse all the moments with the available 50 kOe of the SQUID for both single crystal and powder samples. The shape of the virgin magnetization after zero-field-cool (ZFC) indicates that the high coercive field is due to domain wall pinning. Thus, there are unusual associated anomalies such as asymmetric hysteresis and history dependence. The difference in magnetic hardness of the two compounds suggests that magnetic, electric, and elastic domains are intricately manifested and therefore raise the key question of how the different domains interact.

Coupling of Magnetic and Elastic Domains in the Organic–Inorganic Layered Perovskite‐Like (C6H5C2H4NH3)2FeIICl4Crystal

“…This is due to the very strong antiferromagnetic interaction. Similar observations were made for the χ T values of (CH 3 NH 3 ) 2 Fe II Cl 4 and (C 2 H 5 NH 3 ) 2 Fe II Cl 4 …”

“…The strong antiferromagnetic interaction and the low moment suggest that the long‐range magnetic order of this compound is to a canted antiferromagnetic ground state with spins tilted slightly to the a ‐axis. The canting angle estimated by using M rem = M sat sin ϕ is 0.53° and it is comparable to those of (CH 3 NH 3 ) 2 Fe II Cl 4 and (C 2 H 5 NH 3 ) 2 Fe II Cl 4 . The canting is controlled by the Dzyaloshinskii–Moriya (DM) interaction originating from antisymmetric coupling of nearest neighbor carrier moments …”

“…The organic–inorganic layered perovskite‐like (C 2 H 5 NH 3 ) 2 Fe II Cl 4 is a multiferroic exhibiting canted antiferromagnetism and ferroelasticity . Therefore, it is possible that magnetic properties can be controlled by mechanical stress if the coupling of these ferroic orders exists.…”

High-temperature ferroelastic phase transition in a perovskite-like complex: [Et4N]2[PbBr3]2

“…Whereas in the HTP, with each Pb1 atom occupying the 3m symmetry site, the Pb-Br bond distance changes to 3.030(1)Å and the Br-Pb-Br bond angles are in the range from 81.59 (10) to 98.41 (10) . The C-N bond lengths vary from 1.480(2) to 1.500(2)Å and the C-N-C bond angles vary from 108.40 (18) to 110.60 (18) (Table S3 †). Whereas in the HTP, the cationic part is completely disordered, the tetraethylammonium cations exhibits disorder over six positions (Fig.…”

Crystal structure, phase transitions, optical and electrical properties in a new Cu-halide organic-inorganic hybrid

“…These types of materials have also received much attention owing their interesting molecular shapes. Moreover, the hybrid compounds have stimulated modern-day materials science research due to their innumerable characteristics such as flexibility, specific structural architectures and potential phase transition materials [12][13].…”