Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
J Phys Condens Matter. 2013 Jul 24;25(29):295502. doi: 10.1088/0953-8984/25/29/295502. Epub 2013 Jun 27.
Hybrid organic-inorganic compounds are an intriguing class of materials that have been experimentally studied over the past few years because of a potential broad range of applications. The electronic and magnetic properties of three organic-inorganic hybrid compounds with compositions (NH4)2CuCl4, (CH3NH3)2CuCl4 and (C2H5NH3)2CuCl4 are investigated for the first time with density functional theory plus on-site Coulomb interaction. A strong Coulomb interaction on the copper causes a relatively weak exchange coupling within the layers of the octahedral network, in good agreement with experiment. The character of the exchange interaction (responsible for magnetic behavior) is analyzed. The calculations reveal that (C2H5NH3)2CuCl4 has the strongest Jahn-Teller (JT) distortion in comparison with the two other compounds. The easy axis of magnetization is investigated, showing a weak anisotropic interaction between inter-layer Cu(2+) ions in the (C2H5NH3)2CuCl4 structure. Orbital ordering is concluded from our partial density of states calculations: a cooperation of the JT distortion with an antiferro-distortive pattern.
混合有机-无机化合物是一类非常有趣的材料，由于其潜在的广泛应用，近年来已经进行了实验研究。本文首次利用密度泛函理论加局域库仑相互作用研究了组成式为(NH4)2CuCl4、(CH3NH3)2CuCl4和(C2H5NH3)2CuCl4 的三种有机-无机混合化合物的电子和磁性质。铜上的强库仑相互作用导致八面体网络层内的交换耦合相对较弱，这与实验结果非常吻合。分析了交换相互作用的特性（负责磁行为）。计算表明，与另外两种化合物相比，(C2H5NH3)2CuCl4 具有最强的 Jahn-Teller（JT）畸变。研究了磁化的易轴，表明在 (C2H5NH3)2CuCl4 结构中，层间 Cu(2+) 离子之间存在较弱的各向异性相互作用。我们的部分态密度计算得出了轨道有序的结论：JT 畸变与反铁磁畸变模式的协同作用。
