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Dynamics of electrical conductions for the materials confined in continuous nano-space

连续纳米空间内材料的导电动力学

基本信息

批准号：
15201019
负责人：
TOYOTA Naoki
金额：
$ 31.03万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

项目摘要

In the mesoporous carbon CMK systems, there exist a wide variety of structures. We have carried out the measurements on the electrical conductivities and magnetic susceptibilities in these CMK systems. As a result, we have clarified that low-temperature conducting properties are caused by a two-dimensional variable range hopping mechanism. Under zero-field cooling, the magnetic susceptibility takes a maximum in the vicinity of 60K though, under field cooling, the susceptibilities only exhibit an increase. These facts indicate a formation of spin-glass states in these mesoporous carbon systems. We expect that the spin originates from non-bonding π-electrons in graphen sheets composing the mesoporous structure.In order to detect dynamical properties of low-dimensional electronic systems, we have realized spectroscopic measurement in the range of terahertz frequency. We employ the transmission measurement based on time-domain spectroscopy. The frequency dependence of complex conductivity and complex dielectric constant are determined from 0.1 to 2 THz. Since we have much interests in the low temperature dynamics, the optical cryostat has been installed in the terahertz unit. Now the minimum measuring temperature is achieved to be 2 K. With use of the terahertz spectrometer, we have measured niobium films, self-organizing DNA films and various mesoporous systems to obtain high-frequency dynamics.In addition, the microwave conductivity and infrared spectra were measured for artificially synthesized dry DNA crystals. We have found the importance of the role of primary hydration even in the dry DNA systems.

在介孔碳CMK体系中，存在着多种多样的结构。我们对这些CMK体系的电导率和磁导率进行了测量。因此，我们已经澄清，低温导电性能是由一个二维的可变范围跳跃机制。在零场冷却下，磁化率在60K附近达到最大值，而在场冷却下，磁化率只表现出增加。这些事实表明在这些中孔碳系统中形成自旋玻璃态。我们认为自旋来自于构成介孔结构的石墨烯片层中的非键π电子。为了探测低维电子系统的动力学性质，我们实现了太赫兹频率范围内的光谱测量。我们采用基于时域光谱的透射测量。复电导率和复介电常数的频率依赖性确定从0.1到2太赫兹。由于我们对低温动力学的研究非常感兴趣，所以在太赫兹波段的实验装置中安装了光学低温恒温器。最低测量温度达到2K。利用太赫兹光谱仪，我们测量了铌薄膜、自组织DNA薄膜和各种介孔体系的高频动力学，并测量了人工合成的干DNA晶体的微波电导率和红外光谱。我们已经发现了即使在干燥的DNA系统中初级水合作用的重要性。