On some common features in high and low-Tc superconducting perovskites

Recent photoemission evidence for non-zero gap in highly overdoped Bi2Sr2-CaCu2O8+x, along the directions in the Brillouin zone where the d-wave gap exhibits nodes, is in accordance with more conventional behavior in strongly overdoped high-T-c cuprates. This differs from underdoped regime, where departures from Fermi-liquid (FL) behavior are found. Observed non-FL linear resistivity up to similar to 1050 K in low-T-c perovskite Sr2RuO4-delta is reminiscent of cuprates and implies some similarities between high- and low-T-c perovskites.