We have measured thermoelectric power (TEP) as a function of hole concentration per CuO 2 layer P pl in Y 1−x Ca x Ba 2 Cu 3 O 6 ͑P pl = x /2͒ with no oxygen in the Cu-O chain layer. The room-temperature TEP as a function of P pl , S 290 ͑P pl ͒, of Y 1−x Ca x Ba 2 Cu 3 O 6 behaves identically to that of La 2−z Sr z CuO 4 ͑P pl = z͒. We argue that S 290 ͑P pl ͒ represents a measure of the intrinsic equilibrium electronic states of doped holes and, therefore, can be used as a common scale for the carrier concentrations of layered cuprates. We shows that the P pl determined by this new universal scale is consistent with both hole concentration microscopically determined by NQR and the hole concentration macroscopically determined by the formal valency of Cu. We find two characteristic scaling temperatures, T S * and T S2 * , in the TEP versus temperature curves that change systematically with doping. Based on the universal scale, we uncover a universal phase diagram in which almost all the experimentally determined pseudogap temperatures as a function of P pl fall on two common curves; lower pseudogap temperature defined by the T S * versus P pl curve and upper pseudogap temperature defined by the T S2 * versus P pl curve. We find that while pseudogaps are intrinsic properties of doped holes of a single CuO 2 layer for all high-T c cuprates, T c depends on the number of layers, therefore, the inter layer coupling, in each individual system.

Optical plasma-resonance absorption of Pt island films consisting of Pt particles larger than about 25 Å in diameter has been measured in the photon energy range of 0.5-6.5 eV. As in Rh and Pd island films reported previously, the broadening of the optical plasma-resonance absorption reflects a correlation interaction between conduction electrons. Comparison of the broadening for the Pt island films with that for the Rh island films shows that the correlation interaction is strong when the conduction-electron density n is low. In an electron-gas model, the correlation interaction between electrons becomes stronger with lowering electron density, because the magnitude ratio of the Coulomb to kinetic energy increases as the electron density lowers. Thus, the strong correlation-interaction at low n proves that the correlation interaction in transition metals becomes stronger with magnitude ratio. The magnitude ratio in transition metals is pointed out to increase with lowering n and/or with strengthening d character of conduction electrons. Based on the correlation interaction, reflected by the broadening for the Pt, Rh, and Pd island films, and on the strong correlation interaction, found previously for Ir, the order of magnitude ratio is IrϾPtϾPdϾRh.

Optical absorption of Al island films consisting of Al particles smaller than about 1200 Å in diameter has been measured in the energy range of 0.5-6.5 eV. Below about 200 Å in diameter, parallel band absorption, due to transitions between almost parallel bands, weakens and then disappears with decreasing particle size. Nguyen et al. ͓Phys. Rev. B 47, 3947 ͑1993͔͒ have reported that the parallel band absorption of Al particles is not visible when relaxation times for conduction electrons and the parallel band absorption are much smaller than those in the bulk. We investigate the relaxation times by simulating the optical plasma-resonance absorption of the Al island films with a Maxwell-Garnet-type effective medium theory. The very small relaxation times are pointed out to be a possible cause of the weakening and disappearance.

Copyright 2005 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in E. Anno and M. Tanimoto, Journal of Applied Physics 98(5), 053510 (2005) and may be found at http://link.aip.org/link/?jap/98/053510. publisherOptical absorption of indium-island films, consisting of indium particles smaller than about 500Å in diameter, has been investigated experimentally. The interband absorption, the position of which is almost constant (at about 234 nm) irrespective of particle size, was found to disappear in particle sizes below about 200Å in diameter. This disappearance is pointed out to be similar to that in lead particles, where the disappearance is due to the effect of surface atoms. Optical plasma-resonance absorption appeared at 276-335 nm. By simulating this absorption with a Maxwell-Garnett-type effective-medium theory, we investigated the relaxation time τ and the mean free path l of conduction electrons. Τ and l for particle sizes of about 120 and 160Å in diameter are estimated to be (3.33-3.36)×10^<-16> s and 5.79-5.85Å, respectively, which is smaller than the bulk values (0.38×10^<-14> s and 66.1Å). The small τ and l are attributed to the scattering of the conduction electrons at lattice defects internal to the particles

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