单相ABO3型多铁材料的磁电耦合及磁电性质研究

实验发现多铁性钙钛矿物质YMnO₃和BiMnO₃在接近磁有序相变温度时,其介电常数和正切损失会出现异常，这些现象说明在物质的磁性和介电性质之间存在耦合.通过对系统磁性和铁电性之间可能磁电耦合方式的分析，考虑在系统哈密顿量中加入与自旋关联和极化相关的耦合项，对铁电子系统应用软模理论，对磁性运用基于海森伯模型的量子平均场近似，研究了外磁场诱导的极化、介电的变化和外电场诱导的磁化的变化等，并将以上结果与实验进行了比较和分析，较为合理地解释了一些多铁钙钛矿物质中的磁电现 关键词： 多铁 磁电耦合 铁电 铁磁

Magnetoelectric coupling and magnetoelectric properties of single-phase ABO3 type multiferroic materials

The anomalies in both the dielectric constant and loss tangent occur at fixed temperature close to the magnetic ordering transition, which have been observed experimentally in multiferroic pervoskite YMnO₃ and BiMnO₃, indicating coupling between the magnetism and dielectric properties. In this paper, by analyzing the magnetoelectric coupling between magnetic and ferroelectric subsystems, an appropriate coupling term related to a combination of electric polarization and spin correlation is added to system Hamilton expression, Then apply the soft-mode theory for electric subsystem and mean-field approximation under Heisenberg model for magnetic subsystem,magnetoelectric properties have been investigated, including the change of polarization, dielectric constant induced by external magnetic field, and the change of magnetization induced by external electric field. We also make some qualitative comparison and analysis between our results and the experimented ones and give a reasonable interpretation of magnetoelectricity phenomenon in some multiferroic pervoskite materials.