Xu Lanlan, Liu Qingshi, Meng Junling, Liao Wuping, Liu Xiaojuan, Zhang Hongjie
State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Inorg Chem. 2021 Feb 1;60(3):1367-1379. doi: 10.1021/acs.inorgchem.0c02498. Epub 2021 Jan 12.
Based on first-principles calculations with the DFT + method, the couplings of lattice, charge, spin, and electronic behaviors underlying the Eu-Mn charge transfer in a strongly correlated system of EuMnO were investigated. The potential valence transition from Eu/Mn to Eu/Mn was observed in a compressed lattice with little distortions, which is achieved under hydrostatic pressure and external strain. The intraplane antiferromagnetism (AFM) of Mn is proved to be instrumental in the emergence of Eu. Furthermore, we calculated the magnetic exchange interactions within two equilibrium structures of EuMnO and EuMnO. Mn-Mn ferromagnetic exchange in the -plane is enhanced strongly in the EuMnO structure, contributing to the existence of mixed states. The versatile electronic structures were obtained within the EuMnO phase by imposing different magnetic configurations on the Eu and Mn sublattice, attributed to the coupling of charge transfer and magnetic orderings. It is found that the intraplane ferromagnetic ordering of Mn leads to a metallic electronic structure with the coexistence of Eu and Eu, while the intraplane AFM Mn spin ordering leads to insulating states only with Eu. Notably, a half-metallic characteristic emerges at the magnetic ground state of CF ordering (C-type AFM for the Eu sublattice and ferromagnetic for the Mn sublattice), which makes such a supposed phase more intriguing than the conventional experimental phase. Additionally, the mixture of delocalized 4f with 5d states of Eu in the background of Mn 3d and O 2p orbitals implies a pathway of Eu 4f 5d ↔ O 2p ↔ Mn 3d for charge transfer between Eu and Mn. Our calculation shows that the Eu-Mn charge transfer could be expected in compressed EuMnO and the introduction of Eu 4f states near the Fermi level plays an important role in manipulating the interlinks of charge and spin together with electronic behaviors.
基于采用DFT + 方法的第一性原理计算，研究了EuMnO强关联体系中Eu-Mn电荷转移背后的晶格、电荷、自旋和电子行为的耦合。在几乎没有畸变的压缩晶格中观察到了从Eu/Mn到Eu/Mn的潜在价态转变，这是在静水压力和外部应变下实现的。事实证明，Mn的面内反铁磁性（AFM）有助于Eu的出现。此外，我们计算了EuMnO和EuMnO两种平衡结构内的磁交换相互作用。在EuMnO结构中，面内Mn-Mn铁磁交换显著增强，这有助于混合态的存在。通过在Eu和Mn亚晶格上施加不同的磁构型，在EuMnO相内获得了多样的电子结构，这归因于电荷转移和磁有序的耦合。研究发现，Mn的面内铁磁有序导致了Eu和Eu共存的金属电子结构，而面内AFM Mn自旋有序仅导致Eu的绝缘态。值得注意的是，在CF有序的磁基态（Eu亚晶格为C型AFM，Mn亚晶格为铁磁）出现了半金属特性，这使得这种假定的相比传统实验相更具吸引力。此外，在Mn 3d和O 2p轨道背景下Eu的离域4f与5d态的混合意味着Eu和Mn之间电荷转移的Eu 4f 5d ↔ O 2p ↔ Mn 3d途径。我们的计算表明，在压缩的EuMnO中有望发生Eu-Mn电荷转移，并且在费米能级附近引入Eu 4f态在操纵电荷和自旋的相互联系以及电子行为方面起着重要作用。
