Superconductor and noble metal composite films

Abstract

Films having islands of noble metal protruding from and surrounded by a layer of a superconductor are formed by depositing a layer a noble metal on a substrate, and depositing a superconducting layer at a temperature that converts the noble metal film into puddles. The resulting film is useful as a two-dimensional array of superconductor-normal metal-superconductor Josephson junctions.

We claim:  
     
       1. A composite material film, said composite material comprising: 
       (a) a substrate layer having puddles of noble metal deposited thereon, wherein said puddles of said noble metal layer define a discontinuous film of noble metal puddles in physical contact with said substrate layer, said discontinuous film having a first average thickness; and  
       (b) a superconductor layer comprising superconducting grains and having a second thickness of about 500 Å to about 5000 Å deposited on said substrate layer between said paddles such that:  
       (1) said puddles form islands of noble metal that are in physical contact with said substrate layer and protrude from said substrate through an upper surface of said superconductor layer; and  
       (2) said noble metal also accumulates between said superconducting grains to form a two-dimensional array of superconductor-normal metal-superconductor Josephson junctions.  
     
     
       2. The composite of  claim 1  wherein said substrate is selected from the group consisting of MgO, STO, LAO, and YSZ. 
     
     
       3. The composite of  claim 1  wherein said substrate is any substrate which is suitable for deposition of said noble metal layer and deposition of said superconductor layer. 
     
     
       4. The composite of  claim 1 , wherein said noble metal is selected from the group consisting of Ag, Au, or mixtures thereof. 
     
     
       5. The composite of  claim 4  wherein said noble metal is Ag and said superconductor is YBCO. 
     
     
       6. The composite of  claim 4 , wherein said first average thickness is between about 200 to 4500 Å. 
     
     
       7. The composite of  claim 4 , wherein said first average thickness is between about 800 to 2000 Å. 
     
     
       8. The composite of  claim 4  wherein said noble metal is Au and said superconductor is YBCO. 
     
     
       9. The composite of  claim 4 , wherein said first average thickness is between about {fraction (1/10)}th of said second thickness about 1 times said second thickness. 
     
     
       10. The composite of  claim 4 , wherein said first average thickness is between about 200 to 2000 Å. 
     
     
       11. The composite of  claim 4 , wherein said first average thickness is between about 400 to 600 Å. 
     
     
       12. The composite of  claim 1  wherein said superconductor is selected from the group consisting of YBCO, BSCCO, and thallium based superconductor. 
     
     
       13. The composite of  claim 1  wherein said superconductor is a yttrium basedsuperconductor. 
     
     
       14. The composite of  claim 1  wherein said superconductor is a bismuth based superconductor. 
     
     
       15. A composite material film made by a process comprising the steps of: 
       (a) providing a substrate;  
       (b) forming a noble metal layer having a first thickness upon said substrate; and  
       (c) depositing a superconductor layer including superconducting grains and having a second thickness of about 500 Å to about 5000 Å, at a temperature wherein said metal layer forms puddles exposing regions of substrate and said superconductor deposits between said puddles on said exposed regions of said substrate such that:  
       (1) said puddles form islands of noble metal that are in physical contact with said substrate and protrude from said substrate through an upper surface of said superconductor layer; and  
       (2) said noble metal also accumulates between said superconducting grains to form a two-dimensional array of superconductor-normal metal-superconductor Josephson junctions.  
     
     
       16. A composite material film made by a process comprising the steps of: 
       (a) providing a substrate;  
       (b) forming a noble metal layer having a first thickness upon said substrate;  
       (c) heating said noble metal layer to a sufficient temperature to form puddles of noble metal exposing underlying regions of substrate; and  
       (d) depositing a superconductor layer having a second thickness, and comprising superconducting grains, on said exposed regions of said substrate such that:  
       (1) said puddles form islands of noble metal that are in physical contact with said substrate and protrude from said substrate through said superconductor layer; and  
       (2) said noble metal also accumulates between said superconducting grains to form a two-dimensional array of superconductor-normal metal-superconductor Josephson junctions.