微纳环结构及器件的量子输运与磁响应机制

There exist a series of contradictions between experiments and theory of magnetic response in micro-nano structured rings, challenging the validity of quantum mechanics at mesoscopic scale. In our preliminary studies for this planning project, a new mechanism of magnetic response was obtained for binary periodic mesoscopic ring of finite width. In a period of one magnetic flux quantum, an electronic circling the ring at Fermi face will successively pass through different channels and accumulate an additional phase on each transition between channels, resulting in the changes of persistent current by at least 1-2 orders of magnitude, paramagnetic-diamagnetic transition, and period halving. The results well explain the discrepancies between theory and experiments reported by Science and Phys. Rev. Lett. Based on quantum theory and our theoretical findings, in this project we will explore more widely the persistent current, A-B conductance, and universal conductance fluctuation in micro-nano structures such as nanotubes, nanowires, nanobelts, metal and semiconductor rings, carbon nanotube rings, graphene rings as well as the modulation effects of system's size,disorder, temperature, electron correlation, external fields, and substrate on quantum transport. Some new methods and new theory will be developed for researches of device physics of micro-nano structured rings to obtained the inner association rule and universal law of the magnetic response mechanism. The results will validate the quantum mechanics at mesoscopic scale, and promote understanding of contemporary quantum theory, and provide theoretical basis and technology guidance for the designs and applications of future electromagnetic micro-nano devices and components.

微纳环结构磁响应实验与理论间的矛盾，挑战量子力学在介观尺度上的有效性。前期工作中我们理论发现周期性二元介观环持续电流磁响应的新机制：电子在一个磁流量子周期内先后经过不同通道，通道间的跃迁将累积额外的位相，导致电流幅度数量级改变、顺磁-反磁转变以及半周期的产生。结果很好解释了Science和Phys. Rev. Lett.报道的系列实验与理论的分歧。基于量子理论及我们的理论发现，本项目研究纳米管、纳米线、纳米带、金属和半导体环、碳纳米管环、石墨烯环等新型结构及器件中的持续电流、A-B电导、电导涨落及其磁响应机制，研究系统尺寸、无序、温度、电子关联、外场、基底等对磁响应的调控作用，发展微纳结构器件物理研究的新方法和新理论，探索其磁响应的普适特征和内在关联，有望解决量子力学在介观尺度上的有效性问题，促进人们对当代量子理论的深入理解，并为未来微纳磁电子器件设计和应用提供理论依据和技术指导。

项目中我们研究了不同类型微纳环结构的持续电流及其磁响应特性，研究了不同类型微纳结构的优化结构、电子结构、磁结构、电磁输运等性能，探索了掺杂、无序、温度、自旋耦合等因素对微纳结构器件性能的调制作用。项目组在Nano Lett.、Phys. Rev. B、J. Mater. Chem. C、Adv. Fun. Mater.等国际刊物发表SCI论文28篇，获湖南省自然科学奖二等奖等奖励，见研究成果目录（另有4篇标注的合作论文未列出）。. 项目研究中，我们进一步发现，微纳结构的磁响应特性与原子尺度上的自旋本性及电子多体相互作用密切关联，探索其内在关联及机制具有极大挑战性，但有望在理论源头创新，相关问题仍在我们的持续深入研究中。