Fe（Ⅱ）-N4S2自旋翻转单分子磁体的电子输运性质（英文）

Electronic Transport Properties of Spin-Crossover Magnet Fe（Ⅱ）-N4S2 Complexes

由于其具有高自旋和低自旋磁性双稳态特性，单分子磁体是构建分子自旋电子器件最有潜力的候选体系．基于第一性原理计算和非平衡格林函数方法，我们研究了Fe（II）-N4S2自旋翻转单分子磁体在两个金电极之间的电子结构和输运特性．优化的几何结构参数和计算出来的磁性与实验结果吻合，基于翻转能垒，发现该磁体在可见光范围可实现高低自旋之间的翻转．当磁体处于高自旋态时，其电流在小偏压条件下主要由自旋向下的电子贡献，表现出显著的自旋过滤效应．这些理论研究结果表明此类单分子磁体可用设计分子自旋电子学器件.

Spin-crossover （SCO） magnets can act as one of the most possible building blocks in molec- ular spintronics due to their magnetic bistability between the high-spin （HS） and low-spin （LS） states. Here, the electronic structures and transport properties through SCO magnet Fe（II）-N4S2 complexes sandwiched between gold electrodes are explored by performing exten- sive density functional theory calculations combined with non-equilibrium Green＇s function formalism. The optimized Fe-N and Fe-S distances and predicted magnetic moment of the SCO magnet Fe（II）-N4S2 complexes agree well with the experimental results. The reversed spin transition between the HS and LS states can be realized by visible light irradiation according to the estimated SCO energy barriers. Based on the obtained transport results, we observe nearly perfect spin-filtering effect in this SCO magnet Fe（II）-N4S2 junction with the HS state, and the corresponding current under small bias voltage is mainly contributed by the spin-down electrons, which is obviously larger than that of the LS case. Clearly, these theoretical findings suggest that SCO magnet Fe（II）-N4S2 complexes hold potential applications in molecular spintronies.