Far infrared c-axis optical conductivity in an oriented Bi2Sr2Ca2Cu3O10 polycrystal

Abstract Polarized reflectivity measurements were performed on an oriented Bi 2 Sr 2 Ca 2 Cu 3 O 10 polycrystal. We found that FIR c -axis optical response exhibits similarities with other multilayer compounds such as YBa 2 Cu 3 O x or Bi 2 Sr 2 Ca 1 Cu 2 O 8 . As temperature is decreased, a broad band developing around 450 cm −1 and nearby phonon anomalies are observed. Moreover, two oxygen bond-bending modes are evidenced at 362 and 392 cm −1 . This latter grows in intensity as temperature decreases, contrary to bilayer superconductors. The appearance of the 450 cm −1 broad band is well described by the model of Munzar in which the superconductor is considered as stacked superconducting layers with non equivalent intra-trilayer and interlayer Josephson coupling constants. Our results show that oriented polycrystals are useful to investigate c -axis optical properties of high T c superconductors.