Apostolova Iliana N, Apostolov Angel T, Wesselinowa Julia M
Faculty of Forest Industry, University of Forestry, 1756 Sofia, Bulgaria.
Department of Physics, Faculty of Hydrotechnics, University of Architecture, Civil Engineering and Geodesy, 1046 Sofia, Bulgaria.
Materials (Basel). 2024 Sep 12;17(18):4476. doi: 10.3390/ma17184476.
In a first theoretical investigation of the multiferroic properties of Pb5Fe3F19 (PFF) and Pb5Cr3F19 (PCF), we analyze their magnetic, ferroelectric, and dielectric characteristics as functions of temperature, magnetic field, and ion doping concentration using a microscopic model and Green's function theory. The temperature-dependent polarization in PFF and PCF shows a distinctive kink at the magnetic Neel temperature TN, which vanishes when an external magnetic field is applied, indicating the multiferroic behavior of these two compounds. Ion doping effectively tunes the properties of PFF and PCF. In PFF, Cr ion doping leads to a decrease in the Neel temperature TN, while Cr and Al ion doping lowers the ferroelectric Curie temperature TC. In the case of PCF, we observe the enhancement of TC by Fe ion doping and the reduction by Al ion doping. The last result coincides well quantitatively with the experimental data. Additionally, the magnetodielectric coefficient of PFF is enhanced with the increasing magnetic field.
在对Pb5Fe3F19（PFF）和Pb5Cr3F19（PCF）的多铁性特性进行的首次理论研究中，我们使用微观模型和格林函数理论，分析了它们的磁性、铁电和介电特性随温度、磁场和离子掺杂浓度的变化。PFF和PCF中与温度相关的极化在磁奈尔温度TN处呈现出明显的扭折，当施加外部磁场时该扭折消失，这表明这两种化合物具有多铁性行为。离子掺杂有效地调节了PFF和PCF的性质。在PFF中，Cr离子掺杂导致奈尔温度TN降低，而Cr和Al离子掺杂降低了铁电居里温度TC。在PCF的情况下，我们观察到Fe离子掺杂使TC升高，而Al离子掺杂使其降低。最后一个结果与实验数据在数量上吻合得很好。此外，PFF的磁介电系数随磁场增加而增强。
