In 1911, H. Kamerlingh Onnes discovered that various metals conduct electricity with zero resistance when cooled to very low temperatures. Since then, this phenomenon of superconductivity has been the subject of intense research, as scientists have explored the properties of superconductors and searched for materials that superconduct at higher temperatures and in high magnetic fields. However, although an enormous variety of superconducting materials has been found over the course of the 20th century, it was not until 1979 that the first organic superconductor, (TMTSF)2PF6 was synthesized by Bechgaard. This discovery led to the creation of a wide range of related organic compounds, known as Bechgaard salts, which exhibit a vast array of unique properties.
Following a 1964 paper by Little, it was hoped that organic conductors such as the Bechgaard salts would be high temperature superconductors, even superconducting at room temperature. Disappointingly, no organic superconductor has yet been found with critical temperature (Tc) of greater than 12K. However, Bechgaard salts have many other properties that make them very interesting subjects of research. For example, by varying both temperature and pressure, Bechgaard salts can be forced into almost any phase known to condensed matter physicists (see the accessible phases section for more information). Also, because Bechgaard salts are structurally so different from metallic superconductors, it seems that the standard explanation for superconductivity given by the BCS theory of Bardeen, Cooper, and Schrieffer does not apply very well, and as a result there is a lot of work to be done to understand the mechanism behind superconductivity in these materials.
In this website we hope to have a basic overview of organic superconductors and links to relevant ongoing research and references. The background section describes the basics about superconductors and explains some of the reasons that organic superconductors are interesting. The properties section describes the structure and currently known properties of Bechgaard salts. The experimental work section contains links to the sites of groups that are doing current research in the field of organic superconductors. The references section contains references for background reading and sources for the best currently available quantitative data on organic superconductors.
Funding for organic superconductor research in the Hoffman lab was provided by the National Science Foundation under grant number DMR-0508812.
This organic superconductor website was written by former undergraduates Julia Mundy and Sam Cross.