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Updated: Sep 16, 2025

Measuring Magnetically-Tuned Ferroelectric Polarization in Liquid Crystals
Published on: August 15, 2018
Proton orbital coupling induced magnetic anisotropy in perovskite single crystals: Demonstration with Faraday
Heng Zhi Liu1, Wei-Jie Chen1, Jia Lun Syu1
1Department of Applied Chemistry, National Yang Ming Chiao Tung University, Hsinchu, Taiwan.
Abstract:
In this report, eight halide-based perovskite single crystals high in crystallinity with cations of methylammonium, formamidinium, and cesium are grown at low temperature via a modified solvent evaporation method or an inverse temperature crystallization technique to investigate the Faraday rotation effect. The crystals are examined using various techniques to ensure the pure single crystal phase. Among the crystals investigated, only the MAPbCl3 and MAPbBr3 crystals display the Faraday rotation effect in a broad visible range. Superconducting quantum interference device measurements conducted at room temperature show diamagnetic behavior of all crystals. Contaminations from magnetic elements, which could possibly induce magnetic anisotropy, are excluded from the secondary-ion mass spectrometry results. The experimental results conclude that the spin-orbital coupling of the lead ion is unlikely to be responsible for the observed Faraday rotation effect. The combined effect of the proton orbital-orbital interactions in the CH3NH3 (MA) cation under optical excitation and confinement of the unit cell is proposed as the underlying mechanism for the observed magnetic anisotropy. Furthermore, conclusive results from Faraday rotation measurements conducted on the deuterated d3-CH3ND3PbX3 (X = Cl, Br) and d3-CD3NH3PbCl3 single crystals demonstrate the involvement of the protons in the MA cation in the Faraday rotation effect; however, not all protons contribute equally to magnetic anisotropy.
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