论文标题
基于Cr/Cu的钙钛矿金属有机框架中的抗直觉铁电特性和不可忽略的轨道磁矩
Counter-intuitive Ferroelectric Property And Non-negligible Orbital Magnetic Moment In Cr/Cu Based Perovskite Metal-Organic Frameworks
论文作者
论文摘要
金属有机框架（MOF）具有杂种性质，结合了来自金属离子的无机特性和分子接头的有机特性。 stroppa，\ textit {et al。}表明，钙钛矿类型的mof [c（nh $ _2 $）$ _ 3 $] m [（HCOO）$ _ 3 $]（M = CR，CU）展示了磁磁倍数的多纤维多纤维元素[Angew。化学int。 ed。 50，5847（2011）和Adv。母校。 25，2284（2013）]。此外，它们的铁电性来自混合不当机制，这也解释了磁电耦合。在这项工作中，我们进一步研究了[C（NH $ _2 $）$ _ 3 $] M [（HCOO）$ _ 3 $]的电气和磁性。我们发现，即使没有极性模式，由非极性模式组成的混合模式也会诱导纯电子极化。极性模式补偿了纯电子极化。这导致了违反直觉的论点，即极性模式的反转增强了极化。我们为这种极化特性提供了微观起源和宏观分析。此外，我们发现轨道磁矩与基于Cu的MOF中的自旋贡献相当。最后，我们基于扰动理论建立了轨道磁矩的模型。
Metal-organic frameworks (MOFs) possess a hybrid nature, combining the inorganic properties from the metal ions and the organic properties from the molecular linkers. Stroppa, \textit{et al.}, showed that the perovskite-type MOF [C(NH$_2$)$_3$]M[(HCOO)$_3$] (M = Cr, Cu) exhibits the magneto-electric coupled multiferroicity [Angew. Chem. Int. Ed. 50, 5847 (2011) and Adv. Mater. 25, 2284 (2013)]. Moreover, their ferroelectricity arises from the hybrid improper mechanism, which also explains the magneto-electric coupling. In this work, we further examine the electric and magnetic properties of [C(NH$_2$)$_3$]M[(HCOO)$_3$]. We find that the hybrid mode composed of non-polar modes induces purely electronic polarization even without the polar mode. The polar mode compensates for the purely electronic polarization. It leads to a counter-intuitive argument that the inversion of the polar mode rather enhances the polarization. We provide microscopic origin and macroscopic analysis for this polarization property. In addition, we find that the orbital magnetic moment is comparable to the spin contribution in the Cu-based MOF. Finally, we establish the model for the orbital magnetic moment based on the perturbation theory.
