Huang Jing, Zhuo Yiting, Yang Mingdi, Wang Weiyi, Li Qunxiang
School of Materials and Chemical Engineering, Anhui Jianzhu University, Hefei, Anhui 230601, China.
Department of Chemical Physics & Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China.
Nanoscale. 2025 Jul 31;17(30):17613-17620. doi: 10.1039/d5nr00781j.
Transition metal spin-crossover (SCO) complexes with magnetic bistability show great promise as spin-switches for molecule-based devices. Using first-principles calculations combined with the non-equilibrium Green's function technique, we explored the spin-resolved electronic and transport properties of photochromic Fe(II) SCO complexes in the high-spin state with the open-ring (HS-O) isomer and in the low-spin state with the closed-ring (LS-C) isomer, since the photocyclization and photocycloreversion between the HS-O and LS-C isomers can be reversibly realized under light radiation with different wavelengths at room temperature as in previous experiments. Our results clearly reveal that the examined Fe(II) SCO complexes with photochromic diarylethene-based ligands in the HS-O isomer have lower energy than the LS-C isomer of 0.59 eV. A nearly perfect spin-filtering effect is observed in the proposed molecular junction in the HS-O isomer, in which the Fe(II) SCO complexes are sandwiched between two Au(111) electrodes. The current is carried predominantly by the spin-down electrons within the considered bias voltages, while the spin-up electrons are largely inhibited due to localized molecular orbitals near the Fermi level. At the same time, we also observed an obvious current-switching effect between the HS-O and LS-C isomers, since the current through the molecular devices in the HS-O isomer (acting as the ON state) is significantly larger than that in the LS-C isomer (OFF state). These findings highlight the great potential of this kind of photo-driven SCO complex in future molecular spintronics.
具有磁双稳性的过渡金属自旋交叉（SCO）配合物作为基于分子的器件的自旋开关显示出巨大的潜力。结合非平衡格林函数技术，利用第一性原理计算，我们研究了具有开环（HS-O）异构体的高自旋态和具有闭环（LS-C）异构体的低自旋态的光致变色Fe（II）SCO配合物的自旋分辨电子和输运性质，因为如先前实验所示，HS-O和LS-C异构体之间的光环化和光环化逆转在室温下不同波长的光辐射下可以可逆地实现。我们的结果清楚地表明，所研究的具有光致变色二芳基乙烯基配体的Fe（II）SCO配合物在HS-O异构体中的能量比LS-C异构体低0.59 eV。在所提出的分子结中，在HS-O异构体中观察到了近乎完美的自旋过滤效应，其中Fe（II）SCO配合物夹在两个Au（111）电极之间。在所考虑的偏置电压范围内，电流主要由自旋向下的电子携带，而自旋向上的电子由于费米能级附近的局域分子轨道而受到很大抑制。同时，我们还观察到HS-O和LS-C异构体之间明显的电流切换效应，因为通过HS-O异构体（作为导通状态）的分子器件的电流明显大于通过LS-C异构体（关断状态）的电流。这些发现突出了这种光驱动SCO配合物在未来分子自旋电子学中的巨大潜力。
