Multiferroic Property of 2D Hybrid Organic-Inorganic (C<sub>6</sub>H<sub>5</sub>C<sub>2</sub>H<sub>4</sub>NH<sub>3</sub>)<sub>2</sub>NiCl<sub>4</sub> Perovskite Single Crystals

Recently, two-dimensional (2D) layered organic-inorganic perovskites have been a hot topic not only in photovoltaics but also in optoelectronic applications due to their remarkable optical and electronic properties. In this study, the multiferroic property of the 2D layered (C6H5CH2CH2NH3)2NiCl4, abbreviated PEA-NiCl4, perovskite single crystals has been first reported. The crystals were synthesized by anti-solvent evaporation method by a layer-by-layer mode with relative smooth surface that confirmed by SEM image. The XRD patterns reveal the high crystalline quality with (n00) dominant plane (n = 2, 4, 6, …). The 180° reproducible hysteresis phase loop, butterfly-like amplitude curve, and an effective piezoelectric coefficient of 327 pm/V was evaluated using Piezoelectric Force Microscopy (PFM) measurement. The multiferroic properties has been confirmed by P-E hysteresis loops with PS = 16.3 µC/cm2 Pr = 14.8 µC/cm2, and EC = 6.7 kV/cm and M-H hysteresis loops with HC = 151 G. The 80-nm-width ferroelectric domains orienting along the crystal surface have been observed by the PFM images. This study offers an opportunity to develop new multiferroics material based on 2D layered hybrid perovskite single crystals.