Strong evidence for the three-dimensional Fermi liquid behaviour of quasiparticles in high-TCT_{\rm C} cupurates

It is generally believed that behaviours of quasiparticles (holes) in high-$T_{\rm C}$ cupurates should be attributed to the two-dimensional (2D) electronic states in the CuO$_{2}$ planes. The various anomalies of the transport coefficients for temperatures above $T_{\rm C}$ are long-standing insoluble puzzles and cause serious controversy. Here we reanalyse the published experimental date of LSCO cupurates. We find that the normal-state susceptibility, resistivity, Hall coefficient etc vary precisely as $T^{2}\ln T$ as a function of temperature $T$ in agreement with the prediction of the Fermi liquid model. The quasiparticles are shown to definitely behave as a 3D Fermi liquid. Various attempts to describe the system in terms of non-Fermi liquids,e.g. the RVB state, seem to be erroneous.Comment: 2 pages, 3 Postscript figures, To appear in Physica

Ab initio Evidence for Strong Correlation Associated with Mott Proximity in Iron-based Superconductors

We predict that iron-based superconductors discovered near d6 configuration (5 Fe 3d orbitals filled by 6 electrons) is located on the foot of an unexpectedly large dome of correlated electron matter centered at the Mott insulator at d5 (namely, half filling). This is based on the many-variable variational Monte-Carlo results for ab initio low-energy models derived by the downfolding. The d5 Mott proximity extends to subsequent emergence of incoherent metals, orbital differentiations due to the Mott physics and Hund's-rule coupling, followed by antiferromagnetic quantum criticality, in quantitative accordance with available experiments.Comment: 9 pages, 5 figure

A Spectropolarimetric Test of the Structure of the Intrinsic Absorbers in the Quasar HS1603+3820

We report the results of a spectropolarimetric observation of the C IV mini-BAL in the quasar HS1603+3820. The observations were carried out with the FOCAS instrument on the Subaru telescope and yielded an extremely high polarization sensitivity of 0.1%, at a resolving power of 1500. HS1603+3820 has been the target of a high-resolution spectroscopic monitoring campaign for more than four years, aimed at studying its highly variable C IV mini-BAL profile. Using the monitoring observations, in an earlier paper we were able to narrow down the causes of the variability to the following two scenarios: (1) scattering material of variable optical depth redirecting photons around the absorber, and (2) a variable, highly-ionized screen between the continuum source and the absorber which modulates the UV continuum incident on the absorber. The observations presented here provide a crucial test of the scattering scenario and lead us to disfavor it because (a) the polarization level is very small (p~0.6%) throughout the spectrum, and (b) the polarization level does not increase across the mini-BAL trough. Thus, the variable screen scenario emerges as our favored explanation of the C IV mini-BAL variability. Our conclusion is bolstered by recent X-ray observations of nearby mini-BAL quasars, which show a rapidly variable soft X-ray continuum that appears to be the result of transmission through an ionized absorber of variable ionization parameter and optical depth.Comment: To appear in the Astrophysical Journal, vol. 719, August 201