论文标题
分子连接中振动模式软化的尖锐负差分抗性
Sharp negative differential resistance from vibrational mode softening in molecular junctions
论文作者
论文摘要
我们揭示了在高偏置下单分子电子设备中振动模式软化的关键作用。我们的理论分析是通过最小的分子连接模型进行的，由于二次电子振动耦合而引起的模式软化，并通过开发平均场方法。我们发现，二次电子振动耦合系数的负符号可以在高压下具有较大的峰值与谷化比的高压负差分电阻（NDR）效应。基于硝基取代的寡核（苯基乙烯烯）结的Ab intio参数获得的计算电流 - 电压特性非常吻合。我们的结果表明，振动模式的软化是高压，基础NDR，实质二极管效应和电流分子连接的崩溃的关键作用。
We unravel the critical role of vibrational mode softening in single-molecule electronic devices at high bias. Our theoretical analysis is carried out with a minimal model for molecular junctions, with mode softening arising due to quadratic electron-vibration couplings, and by developing a mean-field approach. We discover that the negative sign of the quadratic electron-vibration coupling coefficient can realize at high voltage a sharp negative differential resistance (NDR) effect with a large peak-to-valley ratio. Calculated current-voltage characteristics, obtained based on ab initio parameters for a nitro-substituted oligo(phenylene ethynylene) junction, agree very well with measurements. Our results establish that vibrational mode softening is a crucial effect at high voltage, underlying NDR, a substantial diode effect, and the breakdown of current-carrying molecular junctions.
