Microwave responses of an insular intrinsic Josephson junction stack fabricated from Bi-Sr-Ca-Cu-O single crystal

The conventional c-axis intrinsic Josephson junction (IJJ) stack is usually fabricated from a piece of single crystal in such a way that it looks like a small mesa sitting on a big pedestal. In some cases the effects of this pedestal should be taken into account in order to explain the experimental observations. To avoid this problem we have developed a novel technique by which we are able to remove a small sample from the single crystal and place it on a substrate with low microwave loss. This enable us to couple it to other microwave devices such as antenna etc. This small sample, or junction stack, measures a few micrometers by a few micrometers in the a-b plane and a few hundred angstroms along the c-axis and is plated with normal metal on both the top and the bottom. To distinguish the structure from the conventional one, we call it an insular intrinsic Josephson junction stack. We carefully study current-voltage characteristics, microwave responses, frequency mixing properties, and discuss the possible applications.