Ghosh Saurabh, Di Sante Domenico, Stroppa Alessandro
School of Applied and Engineering Physics, Cornell University , Ithaca, New York 14850, United States.
Department of Physical and Chemical Sciences, University of L'Aquila , Via Vetoio, 67100 L'Aquila, Italy.
J Phys Chem Lett. 2015 Nov 19;6(22):4553-9. doi: 10.1021/acs.jpclett.5b01806. Epub 2015 Nov 5.
Metal-organic frameworks (MOFs) are hybrid crystalline compounds comprised of an extended ordered network made up of organic molecules, organic linkers and metal cations. In particular, MOFs with the same topology as inorganic perovskites have been shown to possess interesting properties, e.g., coexistence of ferroelectric and magnetic ordering. Using first-principles density functional theory, we have investigated the effect of strain on the compounds C(NH2)3Cr(HCOO)3 and (CH3CH2NH3)Mn(HCOO)3. Here, we show that compressive strain can substantially increase the ferroelectric polarization by more than 300%, and we discuss the mechanism involved in the strain enhancement of polarization. Our study highlights the complex interplay between strain and organic cations' dipoles and put forward the possibility of tuning of ferroelectric polarization through appropriate thin film growing.
金属有机框架（MOFs）是由有机分子、有机连接体和金属阳离子构成的扩展有序网络组成的混合晶体化合物。特别地，具有与无机钙钛矿相同拓扑结构的MOFs已被证明具有有趣的性质，例如铁电和磁有序共存。利用第一性原理密度泛函理论，我们研究了应变对化合物C(NH2)3Cr(HCOO)3和(CH3CH2NH3)Mn(HCOO)3的影响。在此，我们表明压缩应变可使铁电极化大幅增加300%以上，并讨论了应变增强极化所涉及的机制。我们的研究突出了应变与有机阳离子偶极之间复杂的相互作用，并提出了通过适当的薄膜生长来调节铁电极化的可能性。
