Reduced Phonon Dimensionality of Superconductivity in Mesoscopic Scale Structures

这个项目描述了一种研究微纳米结构的新方法，其物理尺寸产生新的效应，因为量子激发的波长具有所涉及的物理结构的尺寸。通过开发制造尺寸小至25 nm的独立金属微结构的能力，有可能将这些微结构与从衬底发出的整体声子分离。这使得声子的态密度可以被系统地控制，从而为研究低维系统的电学和晶格性质提供了一个独特的机会。低声子维度对电子-声子相互作用的影响将通过测量电子的非弹性散射和电子气体的热输运性质来研究。超导体的干涉特性也将使用类似制造工艺制备的材料进行研究。这应该允许将准粒子注入超导体，以及将超导对注入邻近的正常金属。这可以在空间分辨率小于相干长度的情况下完成，从而提供了一种对结中的邻近效应进行“成像”的途径，并可能确定材料中超导转变温度和特征长度之间的关系。

This project describes a new approach to study micro- and nano- fabricated structures whose physical dimensions new effects originating because the wavelength of the quantum excitations have dimensions of the order of the physical structures involved. By exploiting the ability to fabricate free-standing metallic microstructures with dimensions as small as 25 nm, it is possible to decouple these microstructures from the bulk phonons emanating from the substrate. This permits the phonon density of states to be controlled systematically, and thus provides a unique opportunity to study the electrical and lattice properties of low dimensional systems. The consequences of low phonon dimensionality on the electron-phonon interaction will be investigated by measurements of electron inelastic scattering and thermal transport properties of the electron gas. Interference properties of superconductors will also be studied using materials prepared by a similar fabrication process. This should allow the injection of quasiparticles into the superconductor, as well as superconducting pairs into the adjacent normal metal. This can be done with a spatial resolution smaller than the coherence length, thus providing a route to "imaging" proximity effects in junctions and, possibly, providing a determination of the relation between superconducting transition temperatures and characteristic lengths in materials.