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以单个磁性中心的NiO以及由Co和Ni等元素构成的双磁性中心的纳米结构为例,总结了近年所做的主要工作.为了在理论上实现磁性纳米结构中的超快自旋翻转和转移,提出了一种称为Λ进程(Λprocess)的超快自旋转换机理.在实际计算中,首先采用量子化学第一性原理计算得到磁性纳米结构中精确的隙间d电子态,然后考虑外加磁场和自旋轨道耦合分析磁性原子中的自旋局域化程度,最后引入激光脉冲项,研究在其作用下材料的自旋态经由Λ进程实现转换的时间历程.研究结果表明自旋翻转和转移可以在线偏振光的作用下在亚皮秒的时间尺度内完成.为了进一步实现对磁性分子自旋操控的检测和监控,采用附加于磁性中心上的CO分子对磁性分子进行标记.计算得到的与自旋态相关的C—O键振动频率表明自旋操控可以较容易地经由红外光谱实验间接监控.
Taking the single magnetic center NiO and the double magnetic center nanostructures composed of elements such as Co and Ni for example, the main work done in recent years is summarized.In order to theoretically realize the ultrafast spin inversion and transfer in magnetic nanostructures , A fast spin transition mechanism called Λprocess is proposed.In the actual calculation, the exact interstitial d electronic states in the magnetic nanostructures are first calculated by using the quantum chemistry first principle, Magnetic field and spin-orbit coupling analysis of the spin-localized degree of magnetic atoms, and finally the introduction of laser pulses, the material under the action of the spin state through the Λ process to achieve the conversion time course.The results show that the spin flip and The transfer can be done in the sub-picosecond time scale under the action of linear polarized light.In order to further realize the detection and monitoring of spin-manipulation of magnetic molecules, the magnetic molecules are labeled with CO molecules attached to the magnetic center. The C-O bond vibrational frequencies associated with spin states indicate that spin manipulations can be more easily monitored indirectly via IR spectroscopy.