分子结自旋翻转非弹性电输运特性及计算方法研究

项目名称： 分子结自旋翻转非弹性电输运特性及计算方法研究

项目编号： No.11504178

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 数理科学和化学

项目作者： 郭艳东

作者单位： 南京邮电大学

项目金额： 20万元

中文摘要： 近年来，低温扫描隧道显微镜技术的不断发展，使得研究由自旋激发所导致的非弹性电输运成为可能，传导电子与自旋耦合所导致的非弹性散射为我们提供了探测和调控原子尺度磁结构的新手段，对其的研究有助于自旋电子学、量子信息等多个领域的发展。以往计算各类磁性结构电导谱主要采用量子主方程与模型哈密顿量相结合的方法。但此方法待定参数多、求解困难、未考虑实际系统的精细电子结构、且难以推广到较大体系。本项目拟从非平衡格林函数方法(NEGF)出发，借鉴电子-声子耦合非弹性散射电输运的成功经验，在现有理论的基础上，将NEGF与密度泛函理论(DFT)相结合，建立第一性原理框架下适用于实际“分子结”体系自旋翻转非弹性电输运的理论和计算方法。其中，重点解决自洽玻恩近似(SCBA)自能的理论描述及计算方法优化。在此基础上，尝试性地对一些典型体系进行非弹性输运特性和机理的研究。

中文关键词： 电子输运；分子结；自旋翻转非弹性电子输运；格林函数；密度泛函理论

英文摘要： Recently, due to the progress of low-temperature scanning tunneling microscopy, it becomes possible to study the spin excitations and corresponding inelastic electron transport. The inelastic electron transport induced by the electron-spin coupling provides us a new tool to detect and modulate the atomic-scale magnetic structures. The investigation of it will promote the development of spintronics, quantum information, etc. To calculate the conductance spectra of various magnetic nanostructures, a general approach is that of combining the master equation method with a model Hamiltonian. However, there are some shortcomings in this method, e.g., a large number of parameters to be predictive, difficult to solve the equations, ignoring the realistic electronic structures, and difficult to scale to large systems. Inspired by the theory and computational method of spin-phonon coupling induced inelastic electron transport, in this project, we will develop a first-principles method (including both theory and computational method) to study the spin-flip inelastic electron transport in realistic molecular junctions, by combining the nonequilibrium Green’s function (NEGF) and density functional theory (DFT). In particular, we will derive an appropriate self-energy at the level of the self-consistent Born approximation (SCBA). At last, we will try to study the properties and underlying mechanisms of the inelastic electron transport for some typical systems.

英文关键词： electron transport;molecular junction;spin-flip inelastic electron tunneling spectroscopy;Green’s function;density functional theory