Experimental demonstration of superconducting critical temperature   increase in electromagnetic metamaterials
  A recent proposal that the metamaterial approach to dielectric response engineering may increase the critical temperature of a composite superconductor-dielectric metamaterial has been tested in experiments with compressed mixtures of tin and barium titanate nanoparticles of varying composition. An increase of the critical temperature of the order of 0.15 K compared to bulk tin has been observed for 40% volume fraction of barium titanate nanoparticles. Similar results were also obtained with compressed mixtures of tin and strontium titanate nanoparticles. 
Vera N. Smolyaninova, Bradley Yost, Kathryn Zander, M. S. Osofsky,   Heungsoo Kim, Shanta Saha, R. L. Greene, Igor I. Smolya...
physics.optics cond-mat.supr-con