Spin Polarized Current Injection Through HgBr2 Intercalated Bi2212 Intrinsic Josephson Junctions

To investigate the effect of polarized current on tunneling characteristics of intrinsic Josephson junctions (IJJs), spin- polarized and spin-degenerate current have been injected through the c-axis of HgBr₂ intercalated Bi_2.1Sr_1.5Ca_1.4Cu₂O_8+delta (Bi2212) single crystals on which 10 times 10 mum² mesas have been fabricated. These two spin conditions are achieved by depositing either Au (15 nm)/Co (80 nm)/Au (156 nm) multilayers or single Au film on HgBr₂ intercalated Bi2212 with T_c = 74 K followed by photolithography and Ar ion beam etching. The I-V characteristics have been measured with and without a magnetic field parallel to c-axis at 4.2 K. A fine, soft Au wire is used to make a gentle mechanical contact on the top of a particular mesa in the array. Tunneling conductance characteristics were obtained and the magnetic field dependence of sumgap voltage peaks was investigated. These peaks do not change in position with increasing magnetic field for both contact configurations. In addition, the temperature dependence of tunneling characteristics of the IJJs are obtained and existence of pseudogap feature is observed above T_c for HgBr₂ intercalated Bi2212.