考虑到Landau自由能在平衡态时必须是稳定的以及Landau唯象模型中的每一个序参量都必须是实数,BiFeO_3材料的Landau自由能展开系数被重新计算.利用这些参数,模拟了电滞回线、磁滞回线和随外加磁场变化的磁电耦合系数,理论结果与最近报道的实验结果吻合得很好.
Considering both Landau free energy at thermodynamic equilibrium state should be stable and every order parameter should be real in extensive Landau-type phenomenological theory, we have obtained Landau expansion coefficients of BiFeO_3 materials. The magnetization hysteresis loop, polarization hysteresis loop, and the magnetic field dependence of the magnetoelectric coefficient are calculated, which are in good agreement with experimental data reported in previous literatures.
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