Molecular analogue of the perovskite repeating unit and evidence for direct MnIII-CeIV-MnIII exchange coupling pathway

Abstract

The perovskite manganites AMnO3 and their doped analogues A1–xBxMnO3 (A and B = main group and lanthanide metals) are a fascinating family of magnetic oxides exhibiting a rich variety of properties. They are thus under intense investigation along multiple fronts, one of which is how their structural and physical properties are modified at the nanoscale. Here we show that the molecular compound [Ce3Mn8O8(O2CPh)18(HO2CPh)2] (CeIII 2CeIVMnIII 8; hereafter Ce3Mn8) bears a striking structural resemblance to the repeating unit seen in the perovskite manganites. Further, magnetic studies have established that Ce3Mn8 exhibits both the combination of pairwise MnIII 2 ferromagnetic and antiferromagnetic exchange interactions, and the resultant spin vector alignments that are found within the 3-D C-type antiferromagnetic perovskites. First-principles theoretical calculations reveal not only the expected nearest-neighbor MnIII 2 exchange couplings via superexchange pathways through bridging ligands but also an unusual, direct MnIII–CeIV–MnIII metal-to-metal channel involving the CeIV f orbitals.

Exchange Spin Coupling from Gaussian Process Regression

“…Interactions between unpaired electrons localized on metal centers are an important feature of the active sites of many metalloenzymes 1 , artificial catalysts 2 , and molecular magnets with possible applications such as data storage, quantum computing or magnetic materials [3][4][5][6][7][8][9][10][11] . Such interactions are usually not mediated directly by magnetic interactions due to the distance between the spin centers, but rather via a combination of Coulomb interaction and exchange interactions resulting from the Pauli exclusion principle.…”

First-Principles study of an S = 1 quasi-1D quantum molecular magnetic material

“…Overall, our results show that, although our estimate is of the right order of magnitude using a tight-binding model in the Wannier basis, using energetics and fitting to a Heisenberg model provides better J coupling values compared to experiment. What we gain from our Wannier analysis 25 is more insight into the orbital contributions to the superexchange pathway.…”

Long-Range Magnetic Exchange Pathways in Complex Clusters from First Principles

“…5−7 Molecular Mn m Ce n oxo clusters, first reported in 2003, 8 have been synthesized recently to study a variety of magnetic interactions involving f electrons. 9,10 Analogies have been drawn to bulk perovskite manganites, 9 where magnetic interactions are rich and complex and later long-range ferromagnetic couplings are observed. 10 For magnetic insulators, the guiding principle for the understanding of exchange couplings has been Anderson's superexchange theory.…”