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过渡金属酞菁分子作为二维有机金属框架材料的重要构建单元, 在光学、电子学、磁学等领域展示了潜能. 经理论预测, 一系列具有kagome晶格的二维磁性过渡金属酞菁框架材料(kag-TMPc)在自旋电子学、光电子学领域具有应用前景. 本文采用第一性原理计算, 研究了叠状kag-TMPc基异质结中层间耦合对电磁性质的影响. 结果表明kag-MnPc基异质结能够保持单层材料的带隙特性, 带隙在0.17 eV左右, 其中AA和AB堆垛的kag-MnPc/ZnPc为铁磁性半导体, 磁交换能量在40 meV以上; kag-MnPc/MnPc在从AA堆叠转变至AB堆叠的过程中, 由磁性半金属变成为磁性半导体. 特别地, AB堆叠的kag-CuPc/CoPc异质结具有亚铁磁半导体特征, 并且能带排列方式与层间距相关: 层间距在平衡位置时, 两个自旋方向能带排列均为I型; 当层间距增大0.2 Å时, 在自旋向上能带为I型能带排列, 自旋向下为II型能带排列, 具备自旋相关的光电“开关”特性. 本文的结果表明, 层间耦合效应是调控二维磁性有机材料电子性质的有效方式, 为设计磁场调制的新型电磁和光电器件提供了理论参考.Transition metal phthalocyanine molecules serve as building blocks for two-dimensional (2D) metal-organic frameworks with potential applications in optics, electronics, and spintronics. Previous theoretical studies predicted that a two-dimensional transition metal phthalocyanine framework with kagome lattice (kag-TMPc) has stable magnetically ordered properties, which are promising for spintronics and optoelectronics. However, there is a lack of studies on their heterojunctions, which can effectively tune the properties through interlayer coupling despite its weak nature. Here we use the density functional theory (DFT) to calculate the electronic properties of eight representative 2D kag-TMPc vertical heterojunctions with two different stackings (AA and AB) and interlayer distances. We find that most of the kag-MnPc-based heterojunctions can maintain the electronic properties of monolayer materials with low bandgap. The kag-MnPc/ZnPc is a ferromagnetic semiconductor with magnetic exchange energy above 40 meV, regardless of stacking sequences; the electronic properties of kag-MnPc/MnPc heterojunctions change from magnetic half-metal to magnetic semiconductor during the transition from AA stacking to AB stacking. Interestingly, the AB stacked kag-CuPc/CoPc heterojunction is a ferromagnetic semiconductor, and the spin-polarized energy band arrangement changes with the layer spacing: when the layer spacing is as long as the equilibrium distance, the spin-up and spin-down energy bands are aligned as type II; when the layer spacing increases by 0.2 Å, the spin-up energy bands are aligned as type-I energy bands, while the spin-down energy bands are aligned as type-II energy bands. This distance-dependent spin properties can realize magnetic optoelectronic “switching” and has potential applications in new magnetic field modulated electromagnetic and optoelectronic devices.
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Keywords:
- magnetic material /
- heterojunction /
- first principles /
- metal organic framework








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