SUBGAP STRUCTURES IN INTRINSIC JOSEPHSON-JUNCTIONS OF TL2BA2CA2CU3O10+DELTA AND BI2SR2CACU2O8+DELTA

The current voltage characteristics of intrinsic Josephson junctions i n thin films of Tl2Ba2Ca2Cu3O10+delta and Bi2Sr2CaCu2O8+delta single c rystals show pronounced subgap structures at voltages well below the g ap. These voltages are independent of sample geometry, magnetic field and temperature up to 0.5 T-c. We discuss possible explanations and sh ow that the structures could be explained by a peak in the quasipartic le contribution to the total current. For superconducting superlattice s a subgap peak in the quasiparticle density of states has been predic ted theoretically and could explain our results.