Molecular switches, as one of the functional molecular components, play a vital role in nanoscale logic circuits. Here, the effect of intramolecular proton transfer on the current of single-molecule devices consisting of a keto or enol molecule sandwiched between two magnetic zigzag graphene nanoribbon (zGNR) electrodes is theoretically investigated. The keto and enol tautomers interconvert into each other by intramolecular proton transfer. The results show that the current of the keto molecular device is hardly observed, whereas that of the enol molecular device is significantly enhanced, demonstrating a highly efficient switching effect with the ON/OFF ratio up to 3.4 × 10². Moreover, spin currents of the device with an enol isomer display giant bipolar rectification, with the largest rectification ratio of 1.4 × 10⁵ when the two zGNR electrodes are antiparallely spin-polarized. The underlying mechanism is attributed to the parity matching principle of electronic wave functions in the core molecule and zGNR electrodes. The intramolecular proton transfer completely changes the parity of the electronic wave functions of the core molecule, and the electron tunneling channels around the Fermi energy are thus largely modified, resulting in a significant ON/OFF switching ratio. This work develops a strategy for designing high-performance single-molecule switches.

中文翻译：

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通过分子内质子传递改变电子波函数的奇偶性而设计的高性能单分子开关

分子开关作为功能性分子组件之一，在纳米级逻辑电路中起着至关重要的作用。在这里，理论上研究了分子内质子转移对单分子器件电流的影响，该器件由酮或烯醇分子夹在两个磁性之字形石墨烯纳米带（zGNR）电极之间。酮和烯醇互变异构体通过分子内质子转移相互转化。结果表明，几乎未观察到酮分子装置的电流，而烯醇分子装置的电流得到了显着增强，从而显示出高效的开关效果，其开/关比高达3.4×10 ^2。。此外，具有烯醇异构体的器件的自旋电流显示出巨大的双极整流，当两个zGNR电极反平行自旋极化时，最大整流比为1.4×10 ⁵。潜在的机制归因于核心分子和zGNR电极中电子波函数的奇偶匹配原理。分子内质子转移完全改变了核心分子的电子波功能的奇偶性，从而费米能量附近的电子隧穿通道被大大修饰，从而导致明显的开/关切换比。这项工作为设计高性能单分子开关制定了策略。