Evidence for High Tc Superconducting Transitions in Isolated Al45- and   Al47- Nanoclusters
  Heat capacities measured for Al45- and Al47- nanoclusters have reproducible jumps at ~ 200 K. These jumps are consistent with theoretical predictions that some clusters with highly degenerate electronic states near the Fermi level will undergo a transition into a high Tc superconducting state. An analysis based on a theoretical treatment of pairing in Al45- and Al47- agrees well with the experimental data in both the value of the critical temperature and in the size and width of the jumps in the heat capacity. 
Baopeng Cao, Colleen M. Neal, Anne K. Starace, Yurii N. Ovchinnikov,   Vladimir Z. Kresin, Martin F. Jarrold