Low-Resistivity Contact of YBa 2 Cu 3 O 7-x /Al Joint Bonded at Room Temperature

A joining between YBa 2 Cu 3 O 7- x and aluminum was performed at room temperature employing the surface activation method. After surfaces of both samples were sputter-cleaned by an argon beam in vacuum, activated surfaces were pressed to each other at the pressure of 96 MPa. Although the surface of YBa 2 Cu 3 O 7- x was very rough, a tight joint was obtained. Interface resistance of the joint was measured by the four-probe method. It decreased as temperature was lowered and it was as low as 6×10 -9 Ω·m 2 at 77 K. V-I measurement demonstrated, however, that it did not show an exactly ohmic character, but a slight positive dependence on current.