Room-temperature ferrimagnetism and size-modulated electronic structures in two-dimensional cluster-based metal-organic frameworks
Science China Press
This study is led by Prof. Xingxing Li and Prof. Jinlong Yang (Department of Chemical Physics, University of Science and Technology of China).
The calculations were performed by using the density functional theory (DFT) implemented in the Vienna ab initio simulation package (VASP).
A series of thermodynamically stable 2D cluster-based metal-organic frameworks (MOFs) Fen-(pyz) (n = 1~6) has been constructed by utilizing Fen metal clusters as nodes and nitrogen-containing pyrazine ligands as organic linkers. The results demonstrate that these cluster-based MOFs Fen-(pyz) (n = 1~6) present robust ferrimagnetic (FiM) coupling between pyrazine ligands and Fen (n = 1~6) clusters, where each pyrazine ring captures an electron from the Fen (n = 1~6) clusters to form a radical anion, and then magnetically couples with Fen cations through a strong d–p direct exchange interaction, leading to high Curie temperatures (up to 836 K). Additionally, the electronic and magnetic properties of Fen-(pyz) (n = 1~6) MOFs can be easily adjusted by varying the size of Fen (n = 1~6) clusters. Specifically, the Fen-(pyz) (n=1 and 5) exhibit bipolar magnetic semiconductor (BMS) properties, and the Fen-(pyz) (n=2, 4, and 6) display half semiconductor (HSC) characteristics, with the Fe3-(pyz) functioning as the Dirac half metal. Furthermore, altering the size of Fen clusters also allows for the change of magnetic easy axes from in-plane (n = 1, 2, and 6) to out of plane (n = 3, 4, and 5), with the magnetic anisotropy energies (MAEs) ranging from 0.44 to 9.16 meV per formula.
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