摘要
通过密度泛函理论与非平衡格林函数相结合的方法,对一种四配位Fe(Ⅱ)自旋交叉配合物在高自旋(HS,S=2)和低自旋(LS,S=0)构型下的电子结构和输运性质进行了研究.计算结果表明,在外界刺激下,通过改变Fe—N键键长和配体平面之间的二面角,可以实现配合物在HS和LS态之间的自旋跃迁,与实验测量结果一致.根据计算的输运结果,中心配合物前线轨道中的电子重排对该分子结的输运性质有决定性影响.在低偏压下,通过HS态分子结的电流显著高于LS态的电流,且其电子输运主要由自旋向上的电子贡献,自旋过滤效率接近99.98%,同时还表现出明显的负微分电阻(NDR)效应.
Benefiting from performance control at the molecular level, molecular electronic devices hold great pro-mise for device miniaturization and are considered to be the best candidates to replace conventional electronic devices. As one of the most promising building blocks in molecular spintronics, spin-crossover(SCO) complexes have received increasing attention due to their magnetic bistability between the high-spin(HS) and low-spin(LS) states. In this work, the electronic structure as well as the transport properties of a tetra-coordinated Fe(Ⅱ) spin-crossover complex with two different spin configurations(S=0 and S=2) were investigated using a DFT+NEGF approach, which combines density functional theory(DFT) and non-equilibrium Green′s function(NEGF) techniques. The calculated results reveal that the spin transition between the HS and LS states can be achieved by changing the Fe—N bond lengths and the dihedral angle between the ligand coordination planes under external stimuli, which is in good agreement with previous experimental measurements. According to the calculated transport results, the electron rearrangement in the frontier molecular orbitals of the central complex under bias has a decisive influence on the transport properties of the molecular junction. This results in a significantly higher current through the molecular junction with the HS state than that of the LS state at low bias, and the molecular junction with the HS configuration exhibits near-perfect spin-filtering effects and negative differential resistance(NDR) behavior. Based on this Fe(Ⅱ) SCO complex, a multifunctional molecular device integrating switching, high spin-filtering efficiency, and NDR behavior can be constructed, marking its promising application in molecular electronics and spintronics.
作者
段明杰
高靖萱
边江鱼
李冬雪
王昊天
常鹰飞
DUAN Ming-jie;GAO Jing-xuan;BIAN Jiang-yu;LI Dong-xue;WANG Hao-tian;CHANG Ying-fei(Department of Chemistry,Changchun Normal University,Changchun 130032,China;Faculty of Chemistry,Northeast Normal University,Changchun 130024,China)
出处
《分子科学学报》
CAS
北大核心
2022年第6期545-551,共7页
Journal of Molecular Science
基金
吉林省教育厅科学研究项目(JJKH20220828KJ)
长春师范大学自然科学基金资助项目(2020-005)。
关键词
自旋交叉
电子输运
自旋过滤
负微分电阻
spin-crossover
electron transport
spin-filtering
negative differential resistance
