Magnetic Properties of Layered Hybrid Organic‐Inorganic Metal‐Halide Perovskites: Transition Metal, Organic Cation and Perovskite Phase Effects

Abstract

Understanding the structural and magnetic properties in layered hybrid organic‐inorganic metal halide perovskites (HOIPs) is key for their design and integration in spin‐electronic devices. Here, a systematic study is conducted on ten compounds to understand the effect of the transition metal (Cu2+, Mn2+, Co2+), organic spacer (alkyl‐ and aryl‐ammonium), and perovskite phase (Ruddlesden‐Popper and Dion‐Jacobson) on the properties of these materials. Temperature‐dependent Raman measurements show that the crystals’ structural phase transitions are triggered by the motional freedom of the organic cations as well as by the flexibility of the inorganic metal‐halide lattice. In the case of Cu2+ HOIPs, an increase of the in‐plane anisotropy and a reduction of the octahedra interlayer distance is found to change the behavior of the HOIP from that of a 2D ferromagnet to that of a quasi‐3D antiferromagnet. Mn2+ HOIPs show inherent antiferromagnetic octahedra intralayer interactions and a phenomenologically rich magnetism, presenting spin‐canting, spin‐flop transitions, and metamagnetism controlled by the crystal anisotropy. Co2+ crystals with non‐linked tetrahedra show a dominant paramagnetic behavior irrespective of the organic spacer and the perovskite phase. This study demonstrates that the chemical flexibility of HOIPs can be exploited to develop novel layered magnetic materials with tailored magnetic properties.

Broadband Achromatic Quarter-Waveplate Using 2D Hybrid Copper Halide Single Crystals

“…An orthorhombic unit cell of PEA 2 CuCl 4 was determined from SCXRD, which showed a layered structure composed of inorganic octahedra and organic cation layers, as illustrated in Figure a . The 3d 9 electronic configuration of Cu 2+ gives rise to significant JT distortion. − As shown in Figure b, the weak absorption feature induced by the d–d transition of the copper chloride octahedra can be observed in the NIR (800–1000 nm) region. , The JT distortion plays a crucial role in reducing the energy and results in elongated copper halide octahedra, enabling anisotropic lattice distortions in both out-of-plane and in-plane directions . The presence of in-plane structural anisotropy is essential for generating in-plane optical birefringence which is still challenging for common 2D hybrid halide perovskites.…”

Metal-Dependent Antiferromagnetic Interactions in Ba2MCl6 (M2+ = Co, Fe, Mn)

“…Heat capacity was normalized to the sample mass. Measurements below 1.8 K used a 3 He refrigerator. The contribution of the phonons in the lowtemperature regime arising from the non-magnetic part of the structure was estimated by fitting the observed heat capacity of Ba 2 MgCl 6 in the temperature range of interest.…”

Understanding structural distortions in hybrid layered perovskites with the n = 1 Ruddlesden–Popper structure

“…The intense and sustained study of this family of materials has led to the discovery of many properties that are of interest for applications. Examples include photoluminescence (Stoumpos et al, 2013;Gray et al, 2019), electroluminescence (Lin et al, 2018), ferroelectricity (Liao et al, 2015), low-dimensional magnetism (Asensio et al, 2022) and colossal barocaloric effects (Li et al, 2021;Seo et al, 2022), among others.…”