Bhandary Sumanta, Tomczak Jan M, Valli Angelo
School of Physics, Trinity College Dublin, The University of Dublin Dublin 2 Ireland
Institute of Solid State Physics, Vienna University of Technology 1040 Vienna Austria.
Nanoscale Adv. 2021 Jul 26;3(17):4990-4995. doi: 10.1039/d1na00407g. eCollection 2021 Aug 25.
Among spin-crossover complexes, Fe-porphyrin (FeP) stands out for molecular spintronic applications: an intricate, yet favourable balance between ligand fields, charge transfer, and the Coulomb interaction makes FeP highly manipulable, while its planar structure facilitates device integration. Here, we theoretically design a mechanical spin-switch device in which external strain triggers the intrinsic magneto-structural coupling of FeP through a purely organic embedding. Exploiting the chemical compatibility and stretchability of graphene nanoribbon electrodes, we overcome common reliability and reproducibility issues of conventional inorganic setups. The competition between the Coulomb interaction and distortion-induced changes in ligand fields requires methodologies beyond the state-of-the-art: combining density functional theory with many-body techniques, we demonstrate experimentally feasible tensile strain to trigger a low-spin ( = 1) to high-spin ( = 2) crossover. Concomitantly, the current through the device toggles by over an order of magnitude, adding a fully planar mechanical current-switch unit to the panoply of molecular spintronics.
在自旋交叉配合物中，铁卟啉（FeP）在分子自旋电子学应用方面表现突出：配体场、电荷转移和库仑相互作用之间复杂而有利的平衡使FeP具有高度可操控性，而其平面结构便于器件集成。在此，我们从理论上设计了一种机械自旋开关器件，其中外部应变通过纯有机嵌入触发FeP的固有磁结构耦合。利用石墨烯纳米带电极的化学兼容性和可拉伸性，我们克服了传统无机组装中常见的可靠性和可重复性问题。库仑相互作用与配体场中畸变诱导变化之间的竞争需要超越现有技术水平的方法：将密度泛函理论与多体技术相结合，我们证明了实验上可行的拉伸应变可触发低自旋（S = 1）到高自旋（S = 2）的转变。与此同时，通过该器件的电流切换幅度超过一个数量级，为分子自旋电子学增添了一个完全平面的机械电流开关单元。
