Adriana Moreo (University of Tennessee at Knoxville)
An overview of the historic and current developments in superconductivity will be be presented. The phenomenon of superconductivity was discovered almost 100 hundred years ago and it is still one of the hottest research topics providing fascinating puzzles and challenges to both theoreticians and experimentalists. There was a lag of almost 50 years between the experimental discovery of (low T_c) superconductivity and the development of the BCS theory which explained the phenomenon in terms of pairs of electrons held together by the interaction with the phonons in the material. The quest to discover superconducting materials with higher T_c's continued quietly for many years until huge progress occurred in the 1980' when T_c's higher than 77K were observed in copper-oxide based materials. The study of these new materials generated tremendous advances in both experimental and theoretical methods and much is now known about their properties; but the mechanism, i.e., the "glue," that binds the electrons together is still unknown; it appears that phonons are unable to do the job and there is controversy on whether the magnetism present in these materials helps or hurts. Very recently, in 2008, high T_c was discovered in a new family of iron based materials. While they are similar to the cuprates in some ways, i.e., magnetism is present, there are many differences as well. This discovery provides a new chance to unveil the high-T_c mystery and the condensed matter community is intensely working on the subject.