Anomalies in the infrared spectra of underdoped Bi2Sr2CaCu2Oz as evidence for the intrabilayer Josephson effect - art. no. 060502

It was found that the c-axis optical conductivity spectra of underdoped Bi2 Sr2CaCu2Oz exhibit an anomalous increase of the electronic background aroun d 450 cm(-1) below T-c, accompanied by several phonon anomalies. Our observ ations confirm that these features, so far observed only in high-T-c compou nds with considerably higher c-axis conductivity, are common in the family of underdoped bilayer cuprates. The data can be well understood within a mo del involving variations of the electric field inside the unit cell and the intrabilayer Josephson effect. Some differences from the cases of the othe r cuprates are attributed to a highly insulating property of the blocking l ayers.