Research Laboratory for Surface Science, Okayama University, Okayama 700-8530, Japan.
Nature. 2010 Mar 4;464(7285):76-9. doi: 10.1038/nature08859.
Efforts to identify and develop new superconducting materials continue apace, motivated by both fundamental science and the prospects for application. For example, several new superconducting material systems have been developed in the recent past, including calcium-intercalated graphite compounds, boron-doped diamond and-most prominently-iron arsenides such as LaO(1-x)F(x)FeAs (ref. 3). In the case of organic superconductors, however, no new material system with a high superconducting transition temperature (T(c)) has been discovered in the past decade. Here we report that intercalating an alkali metal into picene, a wide-bandgap semiconducting solid hydrocarbon, produces metallic behaviour and superconductivity. Solid potassium-intercalated picene (K(x)picene) shows T(c) values of 7 K and 18 K, depending on the metal content. The drop of magnetization in K(x)picene solids at the transition temperature is sharp (<2 K), similar to the behaviour of Ca-intercalated graphite. The T(c) of 18 K is comparable to that of K-intercalated C(60) (ref. 4). This discovery of superconductivity in K(x)picene shows that organic hydrocarbons are promising candidates for improved T(c) values.
人们一直积极努力地鉴别和开发新的超导材料，这既是出于基础科学研究的需要，也为了发掘超导材料的应用前景。例如，在最近一段时间里，人们已经开发出了几种新的超导材料体系，包括钙插层石墨化合物、掺硼金刚石以及最为突出的铁砷化物，如 LaO(1-x)F(x)FeAs（参考文献 3）。然而，在过去的十年中，有机超导体并未发现具有高超导转变温度（T(c)）的新材料体系。在这里，我们报告说，将碱金属嵌入到并五苯（一种宽带隙半导体固体碳氢化合物）中会产生金属行为和超导性。固态钾插层并五苯（K(x)picene）的 T(c)值取决于金属含量，分别为 7 K 和 18 K。在转变温度下，K(x)picene 固体的磁化强度下降幅度很大（<2 K），类似于 Ca 插层石墨的行为。18 K 的 T(c)与 K 插层 C(60)相当（参考文献 4）。这项在 K(x)picene 中发现超导性的研究表明，有机碳氢化合物是提高 T(c)值的有前途的候选材料。
