Spin tunneling in Co/Au/I/BiSrCaCuO tunnel junctions

Conductance spectra of Co/Au/I/Bi2Sr2CaCu2Ox + 8(BSCCO) tunnel junctions ha ve been measured to investigate the tunneling of spin polarized quasipartic les. BSCCO thin films prepared by molecular beam epitaxy are used for the C o/Au/I/BSCCO tunnel junctions because those have flat surface without any l arge steps as observed on the cleaved surface of single crystals. The super conducting gap is clearly observed in the conductance spectra at the temper ature below the critical temperature T-c. In addition, a splitting of the z ero bias conductance peak and the imbalance of the peak heights are observe d. This feature is induced by the spin polarization of quasiparticles injec ted into the superconductors. (C) 2001 American Institute of Physics.