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.