PLANAR TUNNELING JUNCTIONS ON Y1-XPRXBA2CU3O7-Y FILMS

Tunneling characteristics of planar tunneling junctions on Y1-xPrxBa2C u3O7-y films are presented. Y1-xPrxBa2Cu3O7-y films with x = 0-0.45 we re prepared by laser ablation on MgO(100) substrates. Pb, Au, In or Al counter-electrode was deposited on top of the native barrier. The tun neling characteristics at various temperatures were measured. The gap- like structures of YBCO as well as Pb energy gap and phonon structures were observed in YBCO/Pb junction at 4.2 K. Less pronounced structure s were observed in the case of YPBCO junctions. Junctions with In and Au counter-electrodes have similar characteristics to those with Pb, e xcept that Au junctions with small resistance develop an Andreev refle ction at zero bias. For YPBCO/Al junctions, a large resistance peak ar ound zero blas at low temperature was observed.