Superconductivity in a strongly interacting two-dimensional electron liquid: Gap structure

Both the ac conductivity and the local dynamic spin response function of the commensurate flux phase of the t-J model in two dimensions are computed near half filling. This purported anyonic superconductor shows two different zero-temperature gaps in these quantities, which correspond to the gap for quasiparticle charge excitations and quasiparticle spin excitations, respectively. In both instances, the gap exists over the entire Fermi surface. The ac conductivity also shows the expected Drude δ-function peak with a weight that scales with the hole concentration and with an optical mass given by 2.95 in units of the band mass, (2t)-1. This value agrees with that obtained from exact cluster calculations on the t-J model