Conducting polymer superconductor

This chapter is divided into a number of sections that describe important details related to the conductive polymer/superconductor structures. First, information is provided concerning the preparation and characterization of various polymer/superconductor structures. Chemical and electrochemical deposition methods for localizing the polymers onto a number of cuprate phases are discussed. Section III is devoted to relevant background information related to the induction of superconductivity into metals and semiconductor systems via the proximity effect. More specifically, the four basic methods that have been used to study the occurrence of proximity effects in classical solid-state conductors are described (i.e., contact resistance, modulation of superconductivity in normal/superconductor bilayer structures, passage of supercurrent through superconductor/ normal/superconductor systems, and theoretical analyses). Sections IV and V are devoted to experimental studies of conductive polymer/superconductor interface resistances and modulation of superconductivity in the hybrid systems. Finally, there is a discussion of the initial experimental results that explores the possible induction of superconductivity into organic materials. 

II. SYNTHESIS AND CHARACTERIZATION OF CONDUCTIVE POLYMER/SUPERCONDUCTOR ASSEMBLIES... 

Schottky diodes, metal-insulator-semiconductor diodes, MIS field-effect transistors, and light-emitting diodes have all been prepared by using these polymeric materials [13-17]. With the discovery of high temperature superconductivity, new opportunities exist for the development of hybrid conductive polymer/superconductor systems in which the unique properties of the conducting polymers complement the properties of high-Tc superconductors for novel applications. 

V. MODULATION OF SUPERCONDUCTIVITY IN CONDUCTIVE POLYMER/SUPERCONDUCTOR BILAYER STRUCTURES... 

Although deposition conditions for the preparation of YBa2Cu307-5 films are often optimized to produce c-axis-oriented films that exhibit high critical currents, polycrystalline films appear to be better suited for the fabrication of sensitive conductive polymer/superconductor structures. These superconductor thin films are more textured and have lower critical currents than the smooth films, which are prepared with what would normally be considered more optimized deposition conditions. The weak link characteristics of these thin films are also enhanced by depositing the superconductor onto cleaved MgO substrates. These substrates possess natural step edges and can be exploited to further disrupt the connection between selected superconductor grains. 

In summary, effective methods have been identified for the preparation of conductive polymer/superconductor and molecular metal/superconductor composite structures. Here both solution-processing strategies and electrochemical deposition techniques for the preparation of the composite structures have been developed. Moreover, a powerful new high-Tc self-assembly method based on the spontaneous adsorption of amine reagents onto cuprate surfaces has been developed that affords precise control of the synthesis of polymer/superconductor composite systems. With these methods, the hybrid structures can be prepared with little chemical or physical damage to either conductor component material. Convincing evidence for the clean combination of the molecular and superconductor components has been obtained from electrochemical, conductivity, contact resistance, and electron microscopic measurements. 

Conductive Polymer/Superconductor Structures as Chemical Sensors... 

High-temperature superconductors, p. 192 Fuel cells, p. 579 Nanotubes, p. 608 Self-assembling materials, p. 649 Conducting polymers, p. 772... 

For these volumes in the Springer book review series Topics in Current Chemistry, it seemed natural to blend a mix of theory and experiment in chemistry, materials science, and physics. The content of this volume ranges from conducting polymers and charge-transfer conductors and superconductors, to single-molecule behavior and the more recent understanding in single-molecule electronic properties at the metal-molecule interface. 

The optical properties of conducting polymers are important to the development of an understanding of the basic electronic structure of the material. These and other problems were described in various books and review papers [90-93]. Raman spectroscopy is also an ideal tool for predicting many important electronic properties of molecular materials, organic conductors, and superconductors as well as for understanding their different physical properties, since it is a nondestructive tool, which can be used in situ and with spatial resolution as good as 1 xm. 

We start our discussion with simple concepts from the band theory for solids, discuss what can break the symmetry of one-dimensional systems, introduce electrical conductivity and superconductivity, present the Mulliken charge transfer theory for solution complexes and its extension to solids, then discuss briefly the simple tt electron theory for long polyenes. Other articles in this volume review the detailed interplay between structure and electronic properties of conductors and superconductors [206], and electrical transport in conducting polymers [207],... 

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