A method was presented for the separate study of the electrical transport properties of the grain boundaries which were formed at the top and bottom edges of step-edge Josephson junctions. Step-edge junctions were prepared on (100) LaAlO3 steps by using tilted Ar ion milling to define the electrodes and micro-bridges. Due to the shadowing effect of the step, a continuous Cu3Ba2YO7 stripe remained along, and at the bottom of, the step on both sides of a micro-bridge. It was found that the top grain boundary was responsible for the weak-link behavior of the step-edge junctions. The transport properties were related to the differing microstructural properties of the 2 grain boundaries which formed at the edges of the step.

F.Lombardi, Z.G.Ivanov, G.M.Fischer, E.Olsson, T.Claeson: Applied Physics Letters, 1998, 72[2], 249-51