Bismuth based oxide superconductor thin films and method of manufacturing the same

Abstract

A Bi-based oxide superconductor thin film whose c-axis is oriented parallel to the substrate and whose a-axis (or b-axis) is oriented perpendicular to the substrate, is manufactured in order to obtain a high performance layered Josephson junction using a Bi-based oxide superconductor. The method of manufacturing an a-axis oriented Bi-based oxide superconductor thin film, involves an epitaxial growth process using an LaSrAlO 4 single crystal substrate of a (110) plane or a LaSrGaO 4 single crystal substrate of a (110) plane, for which the lattice constant matches well with a (100) plane of a Bi-2223 oxide superconductor. By this method, rather than the normally easily obtained Bi-2212, an a-axis oriented film of Bi-2223 showing an extremely high superconductive transition temperature even for a Bi-based oxide superconductor can be selectively manufactured.

1 . A method of manufacturing an oxide superconductor thin film on a substrate, wherein a lattice constant of a single crystal of said superconductor thin film is approximately integer times multiple of a lattice constant of a single crystal of said substrate. 
   
   
       2 . A method of manufacturing an oxide superconductor thin film according to  claim 1 , wherein said oxide superconductor thin film is a Bi 2 Sr 2 Ca 2 Cu 3 O 10±X  (where X is a positive number less than unity) or a Bi 2 Sr 2 CuO 6±Y  (where Y is a positive number less than unity) thin film. 
   
   
       3 . A method of manufacturing an oxide superconductor thin film according to  claim 1 , wherein said single crystal substrate is selected from the group consisting α-Al 2 O 3  and NdAlO 3 . 
   
   
       4 . A method of manufacturing an oxide superconductor thin film according to  claim 2 , wherein said single crystal substrate is selected from the group consisting α-Al 2 O 3  and NdAlO 3 . 
   
   
       5 . An oxide superconductor thin film deposited on a substrate, wherein a lattice constant of a single crystal of said thin film is an approximate integer multiple of a lattice constant of a single crystal of said substrate. 
   
   
       6 . An oxide superconductor thin film according to  claim 5 , wherein said oxide superconductor thin film is represented by Bi 2 Sr 2 Ca 2 Cu 3 O 10±X  (where X is a positive number less than unity) or Bi 2 Sr 2 CuO 6±Y  (where Y is a positive number less than unity). 
   
   
       7 . An oxide superconductor thin film according to  claim 5 , wherein said superconductor thin film is deposited on a single crystal substrate selected from the group consisting of α-Al 2 O 3  and NdAlO 3 . 
   
   
       8 . An oxide superconductor thin film according to  claim 6 , wherein said superconductor thin film is deposited on a single crystal substrate selected from the group consisting of α-Al 2 O 3  and NdAlO 3 . 
   
   
       9 . A Josephson device manufactured using an oxide superconductor thin film according to  claim 5 . 
   
   
       10 . A Josephson device manufactured using an oxide superconductor thin film according to  claim 6 . 
   
   
       11 . A Josephson device manufactured using an oxide superconductor thin film according to  claim 7 . 
   
   
       12 . A Josephson device manufactured using an oxide superconductor thin film according to  claim 8 . 
   
   
       13 . A method of manufacturing a Bia 2 Sr 2 Ca 2 Cu 3 O 10±X  (where X is a positive number less than unity) oxide superconductive film, wherein the Bi 2 Sr 2 Ca 2 Cu 3 O 10±X  superconductor oxide film is manufactured by carrying out epitaxial growth of Bi 2 Sr 2 Ca 2 Cu 3 O 10±X  on a (10-10) crystal plane of a single crystal substrate of a α-Al 2 O 3  or on a (10-10) crystal plane of a single crystal substrate of NdAlO 3  such that a c-axis of the Bi 2 Sr 2 Ca 2 Cu 3 O 10  oxide is oriented parallel to the said substrate and an a-axis or b-axis is oriented perpendicular to the substrate surface. 
   
   
       14 . A Bi 2 Sr 2 Ca 2 Cu 3 O 10±X  (where X is a positive number less than unity) oxide superconductive film, obtained by epitaxial growth of Bi 2 Sr 2 Ca 2 Cu 2 O 10±X  on a (10-10) crystal plane of a single crystal substrate of α-Al 2 O 3  or on a (10-10) crystal plane of a single crystal of NdAlO 3  such that a c-axis of the Bia 2 Sr 2 Ca 2 Cu 3 O 10±X  oxide film is oriented parallel to the said substrate and an a-axis or b-axis is oriented perpendicular to the substrate surface. 
   
   
       15 . A Josephson device manufactured using a Bia 2 Sr 2 Ca 2 Cu 3 O 10±X  oxide superconductor thin film according to  claim 14 .