Microstructure of superconducting Y₁Ba₂Cu₃O_7-x/Nd_1.85Ce_0.15CuO_4-y bilayer films

Abstract

Superconducting bilayers of Y 1 Ba 2 Cu 3 O 7-x (YBCO) and Nd 1.85 Ce 0.15 CuO 4-y (NCCO) are of particular interest for the study of the interaction between p -type superconductors(YBCO) and n -type superconductors for possible device applications. The microstructural study is crucial since the crystallinity and interface quality of the bilayers effect the characteristics of heterojunctions. In this report, we present details of the microstructure of superconducting NCCO/YBCO bilayers. NCCO/YBCO bilayers were deposited on three different single crystal substrates of (001) LaAlO 3 , (001) SrTiO 3 , and (001) Y-ZrO 2 (YSZ) using pulsed laser depositon. The details of the deposition and superconducting properties are reported elsewhere. The samples reported in this report have typical YBCO thickness of 2000 A and NCCO thickness of 4000 A. Figure 1(a) shows a bright field image of a NCCO/YBCO bilayer grown on YSZ and exhibits a Moire’ fringe pattern in some regions of the NCCO film. The Moire’ fringes have a spacing of ∼ 31.01 Å.