金属-绝缘体转变附近纳米金属颗粒膜的电子输运性质研究

纳米金属颗粒薄膜材料具有独特的力学、光学和电磁学性质，在光伏、发光、新型传感器等领域具有巨大的应用潜力，同时纳米金属颗粒薄膜中金属体积分数和颗粒尺寸容易调控，因而是研究介观物理的良好材料体系。本项目拟在已有研究的基础上，制备具有不同金属体积分数、不同颗粒尺寸的系列非磁性纳米金属颗粒膜及超导-绝缘体颗粒膜，并制备相应的“金属颗粒膜/绝缘体/金属”隧道结，测量金属-绝缘体转变附近样品的电子输运性质和隧道谱。研究内容包括：(1) 研究非磁性纳米金属颗粒膜的霍尔迁移率在金属-绝缘体转变附近是否存在突变及其物理原因；(2) 实验研究金属颗粒间电子的库仑相互作用对电子能态密度及金属-绝缘体转变附近电导率和霍尔输运的影响；(3) 实验研究三维超导-绝缘体颗粒膜中是否存在一个超导-绝缘体转变的普适临界隧穿电阻，研究具有准重入超导现象样品的电子能态密度谱线随温度的变化规律，探求准重入超导现象的物理机理。

Nanogranular metals combine the unique properties of individual and collective properties of coupled nanocrystals opening a new route for potential novel electronic, optical, and optoelectronic applications. The ease of adjusting electronic properties of granular metals makes them most suitable for fundamental studies of mesoscopic physics. In this proposal, we will fabricate several series of nonmagnetic nanogranular metal films and superconductor granular films with different volumes fraction of metals and grain sizes. The “granular metal film/insulator barrier/normal metal” type tunneling junction will be also prepared. Thus the electronic transport properties and tunneling spectra of the samples could be measured near the metal-insulator transition. Three parts of investigations are included in the proposal. Firstly, we will test whether there is an abnormal change of the Hall mobility in the nanogranular metal films near the metal-insulator transition, and explore the related mechanisms. Secondly, we will experimentally investigate the influences of Coulomb electron-electron interaction effect on the electronic density of states and longitudinal and Hall transport properties near metal-insulator transition. Finally, we will investigate whether there is a universal tunneling resistance for superconductor-insulator transition. We will measure the tunnel spectra of the films revealing quasireentrant superconductivity near the transition temperatures, and expect to disclose the physical mechanisms of the phenomenon.