尖晶石氧化物CoCr2O4的多铁性研究

为深入理解化合物CoCr₂O₄奇特的多铁性行为，结合尖晶石晶格结构特点，考虑近邻A-A、A-B、B-B及B位离子间次近邻交换耦合的影响，构建经典海森堡自旋模型对磁致铁电行为进行描述，并采用蒙特卡罗模拟对模型进行求解.重点考察不同磁交换耦合作用下，外磁场对体系磁化行为和电极化行为的调控.结果表明：子晶格B1离子贡献了体系的宏观磁化强度和电极化强度；近邻A-A和B位次近邻交换耦合参数的改变对子晶格A位磁性离子的磁电行为没有影响，但对B位离子的磁化强度和电极化强度有显著的调制作用，尤其是来源于子晶格B1的电极化强度对B位次近邻交换耦合参数的改变极为敏感；这些结果反映了立方尖晶石磁结构中A位和B位磁性离子环境及分布对称性的差异.

Investigation on Multiferroicity in Spinel Oxide CoCr2O4

To understand fantastic multiferroicity of CoCr₂O₄, a Heisenberg spin model on three-dimensional spinel lattice was constructed. In the model, we considered multiple magnetic interactions including nearest-neighbor A-A, A-B, B-B couplings as well as next-nearest-neighbor interaction among B sites. Monte Carlo simulation is employed to obtain magnetoelectric quantities. Influences of exchange couplings on magnetoelectric behaviors are emphatically investigated under rotation of magnetic field. It is found that macroscopic magnetization and polarization stem mainly from contributions of B1 ions. With varying exchange couplings of A-A interaction and next-nearest-neighboring B-B interaction among B-site ions, B-site ions exhibit prominent magnetoelectric responses, while A-site ions remain unchanged. It indicates distinct differences between symmetry and magnetic interaction environment for A-site and B-site ions in spinel lattice.