Tunneling spectra of underdoped Bi 2 Sr 2 Ca 1-x Y x Cu 2 O 8+δ intrinsic Josephson junctions

Mesa-structured submicron intrinsic Josephson junctions are successfully fabricated and well characterized on underdoped Bi2Sr2Ca1−xYxCu2O8+δ single crystals with a Tc of 80 K. Tunneling spectra at the temperatures ranging from 4.2 K to 295 K are measured. A pulse technique is used to reduce sample heating for the measurement near pseudogap opening temperature T* ~ 280 K. Our experimental results show that the superconducting gap, the peak-dip separation, and the pseudogap opening temperature are all increased as compared with those from near optimally doped samples, which requires further theoretical analysis in the future.