Department of Chemistry and Research Institute for Basic Sciences, Kyung Hee University, Seoul 02447, Korea.
Max Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany.
Molecules. 2021 Mar 5;26(5):1410. doi: 10.3390/molecules26051410.
We examined the magnetic ground states, the preferred spin orientations and the spin exchanges of four layered phases MPS (M = Mn, Fe, Co, Ni) by first principles density functional theory plus onsite repulsion (DFT + U) calculations. The magnetic ground states predicted for MPS by DFT + U calculations using their optimized crystal structures are in agreement with experiment for M = Mn, Co and Ni, but not for FePS. DFT + U calculations including spin-orbit coupling correctly predict the observed spin orientations for FePS, CoPS and NiPS, but not for MnPS. Further analyses suggest that the ||z spin direction observed for the Mn ions of MnPS is caused by the magnetic dipole-dipole interaction in its magnetic ground state. Noting that the spin exchanges are determined by the ligand p-orbital tails of magnetic orbitals, we formulated qualitative rules governing spin exchanges as the guidelines for discussing and estimating the spin exchanges of magnetic solids. Use of these rules allowed us to recognize several unusual exchanges of MPS, which are mediated by the symmetry-adapted group orbitals of PS and exhibit unusual features unknown from other types of spin exchanges.
我们通过第一性原理密度泛函理论加局域排斥（DFT + U）计算研究了四层相 MPS（M = Mn、Fe、Co、Ni）的磁基态、优先自旋方向和自旋交换。使用优化后的晶体结构进行 DFT + U 计算预测的 MPS 的磁基态与 Mn、Co 和 Ni 的实验结果一致，但与 FePS 不一致。包括自旋轨道耦合的 DFT + U 计算正确预测了 FePS、CoPS 和 NiPS 的观察到的自旋方向，但对 MnPS 则不然。进一步的分析表明，MnPS 中 Mn 离子观察到的 ||z 自旋方向是由其磁基态中的磁偶极-偶极相互作用引起的。注意到自旋交换由磁性轨道的配体 p 轨道尾部决定，我们制定了支配自旋交换的定性规则，作为讨论和估计磁性固体的自旋交换的指南。这些规则的使用使我们能够识别 MPS 的几种不寻常的交换，这些交换由 PS 的对称适应的群轨道介导，并表现出不同于其他类型的自旋交换的不寻常特征。
