Covalent effects in magnetic ferroelectrics MnMO3 (M = Ti, Sn)
Covalent effects in magnetic ferroelectrics MnMO3 (M = Ti, Sn)
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DOI：
10.1002/pssb.201451476
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发表时间：
2015-03
期刊：
影响因子：
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通讯作者：
X. Hao;Yuanhui Xu;C. Franchini;F. Gao
中科院分区：
文献类型：
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作者：
X. Hao;Yuanhui Xu;C. Franchini;F. Gao
通过基于密度泛函理论（DFT）、DFT + U和杂化泛函方法的第一性原理计算，我们报道了高压诱导化合物MnMO3 （M = Ti, Sn）的磁性、电子和铁电性质的比较研究。结果正确地描述了两种化合物的绝缘特性和G型反铁磁基态，与实验观察结果吻合较好。我们用Berry相方法预测了MnTiO3和mnnsno3的大自发铁电极化。特别地，从势能面、玻恩有效电荷和电局域函数的角度，讨论和解释了驱动铁电跃迁的共价相互作用机制。我们的研究结果表明，MnTiO3和MnSnO3是铁电性钙钛矿的独特例子，其中铁电性的不稳定性源于B位原子的几何效应和化学活性的共同作用，从而将0度（MnTiO3）和孤对机制（MnSnO3）的概念扩展到磁性铁电性。
By means of first‐principles calculations based on density functional theory (DFT), DFT + U and hybrid functional methods, we report a comparative study of the magnetic, electronic, and ferroelectric properties of high‐pressure‐induced compounds MnMO3 (M = Ti, Sn). The results correctly describe the insulating character and G‐type antiferromagnetic ground state for both compounds, which is in good agreement with the experimental observations. We predicted large spontaneous ferroelectric polarizations of MnTiO3 and MnSnO3 by using the Berry‐phase method. In particular, the proper covalent interaction mechanism driving the ferroelectric transition is discussed and explained in term of the analysis of potential‐energy surfaces, Born effective charges, and electric localization function. Our results indicate that MnTiO3 and MnSnO3 represent unique examples of ferroelectric perovskites in which the ferroelectric instabilities originate from the combined action of geometric effects and chemical activity of the B‐site atom, thus extending the concept of d0‐ness (MnTiO3) and lone‐pair mechanism (MnSnO3) to magnetic ferroelectrics.