Optical and thermodynamic properties of the high-temperature superconductor HgBa2CuO4+δ

In- and out-of-plane optical spectra and specific heat measurements for the single layer cuprate superconductor HgBa2CuO4+delta (Hg-1201) at optimal doping (T-c=97 K) are presented. Both the in-plane and out-of-plane superfluid density agree well with a recently proposed scaling relation rho(s)proportional to sigma T-dc(c). It is shown that there is a superconductivity induced increase of the in-plane low frequency spectral weight which follows the trend found in underdoped and optimally doped Bi2Sr2CaCu2O8+delta (Bi-2212) and optimally doped Bi2Sr2Ca2Cu3O10+delta (Bi-2223). We observe an increase of optical spectral weight which corresponds to a change in kinetic energy Delta W approximate to 0.5 meV/Cu which is more than enough to explain the condensation energy. The specific heat anomaly is 10 times smaller than in YBa2Cu3O6+delta (YBCO) and 3 times smaller than in Bi-2212. The shape of the anomaly is similar to the one observed in YBCO showing that the superconducting transition is governed by thermal fluctuations.