Structural and electrical transport properties of superconducting Au0.7In0.3 films: A random array of superconductor–normal-metal–superconductor Josephson junctions

Abstract

The structural and superconducting properties of Au0.7In0.3 films, grown by interdiffusion of alternating Au and In layers, have been studied. The films were found to consist of a uniform solid solution of Au0.9In0.1, with excess In precipitated in the form of In-rich grains of various Au-In phases with distinct atomic compositions, including intermetallic compounds. As the temperature was lowered, these individual grains became superconducting at a particular local transition temperature (Tc0), determined primarily by the atomic composition of the grain, before a fully superconducting state of zero resistance was established. From the observed onset temperature of the superconducting transition, it was inferred that up to three different superconducting phases could have formed in these Au0.7In0.3 films, all of which were embedded in a uniform Au0.9In0.1 matrix. Among these phases, the Tc0 of a particular one, 0.8 K, is higher than any previously reported for the Au-In system. The electrical transport properties were studied down to low temperatures. The transport results were found to be well correlated with those of the structural studies. The present work suggests that these Au0.7In0.3 films can be modeled as a random array of superconductor–normal-metal–superconductor Josephson junctions. The effect of disorder and magnetic field on the superconducting transition in these Au0.7In0.3 films is discussed.

Source-reported materials — not catalogue approval

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