Superconducting interconnects with ultra-low thermal conductivity capable of providing a direct connection between a millikelvin temperature environment and a 70 K temperature environment.

An oxide superconductor includes: REBa.sub.2Cu.sub.3O.sub.7-x (RE being one element selected from a RE element group of Pr, Nd, Sm, Eu, Gd, Y, Tb, Dy, Ho, Er, Tm, Yb, and Lu). The RE includes at least three types of metallic elements (M1, M2, and M3), and the three types of metallic elements are any element of the RE element group selected in order. In an oxide system satisfying R(M1)20 mol % and R(M2)60 mol % and R(M3)20 mol %, R(M1) being an average metallic element ratio of M1 in M1+M2+M3, SD(Ms)>0.15 is satisfied at a position at 50% of an average film thickness of a cross section including the c-axis, Ms being the metallic element of not larger of R(M1) and R(M3), SD(Ms) being a standard deviation/average value of a concentration of Ms.

An oxide superconductor of an embodiment includes an oxide superconductor layer having a continuous Perovskite structure including rare earth elements, barium (Ba), and copper (Cu). The rare earth elements include a first element which is praseodymium, at least one second element selected from the group consisting of neodymium, samarium, europium, and gadolinium, at least one third element selected from the group consisting of yttrium, terbium, dysprosium, and holmium, and at least one fourth element selected from the group consisting of erbium, thulium, ytterbium, and lutetium. When the number of atoms of the first element is N(PA), the number of atoms of the second element is N(SA), and the number of atoms of the fourth element is N(CA), 1.5(N(PA)+N(SA))N(CA) or 2(N(CA)N(PA))N(SA) is satisfied.

A superconductor wire having a first HTS layer with a first cap layer in direct contact with a first surface of the first HTS layer and a second cap layer in direct contact with a second surface of the first HTS layer. There is a first lamination layer affixed to the first cap layer and a stabilizer layer having a first surface affixed to the second cap layer. There is a second HTS layer and a third cap layer in direct contact with a first surface of the second HTS layer and a fourth cap layer in direct contact with a second surface of the second HTS layer. There is a second lamination layer affixed to the fourth cap layer. The second surface of the stabilizer layer is affixed to the third cap layer and there are first and second fillets disposed along a edge of the laminated superconductor.

There is set forth herein a superconducting lead assembly comprising: a positive superconducting wire; a negative superconducting wire, wherein the positive superconducting wire is configured to conduct inflow current to a cryogenic apparatus and wherein the negative superconducting wire is configured to conduct outflow current away from the cryogenic apparatus; and an electrically insulating separator, wherein the positive superconducting wire and the negative superconducting wire are arranged proximately one another and on opposite sides of the electrically insulating separator for cancellation of electromagnetic forces attributable to current flowing simultaneously in opposite directions within the positive superconducting wire and the negative superconducting wire, and wherein a length of the superconducting lead assembly is flexible. In one embodiment the positive superconducting wire and the negative superconducting wire can include high temperature superconducting (HTS) material.

A method and composition for doped HTS tapes having directional flux pinning and critical current.

Electrical devices operating in a range of 273 C. to 100 C. are disclosed. The devices include an insulating substrate. A UO.sub.2+x crystal or oriented crystal UO.sub.2+x film is on a first portion of the substrate. The UO.sub.2+x crystal or film originates and hosts a non-equilibrium polaronic quantum phase-condensate. A first lead on a second portion of the substrate is in electrical contact with the UO.sub.2+x crystal or film. A second lead on a third portion of the surface is in electrical contact with the UO.sub.2+x crystal or film. The leads are isolated from each other. A UO.sub.2+x excitation source is in operable communication with the UO.sub.2+X crystal or film. The source is configured to polarize a region of the crystal or film thereby activating the non-equilibrium quantum phase-condensate. One source state causes the UO.sub.2+X crystal or film to be conducting. Another source state causes the UO.sub.2+x crystal or film to be non-conductive.

An oxide superconductor of an embodiment includes an oxide superconductor layer having a continuous Perovskite structure containing rare earth elements, barium (Ba), and copper (Cu). The rare earth elements contain a first element which is praseodymium (Pr), at least one second element selected from the group consisting of neodymium (Nd), samarium (Sm), europium (Eu), and gadolinium (Gd), at least one third element selected from the group consisting of yttrium (Y), terbium (Tb), dysprosium (Dy), and holmium (Ho), and at least one fourth element selected from the group consisting of erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu).

An oxide superconductor includes: REBa.sub.2Cu.sub.3O.sub.7-x (RE being one element selected from a RE element group of Pr, Nd, Sm, Eu, Gd, Y, Tb, Dy, Ho, Er, Tm, Yb, and Lu). The RE includes at least three, types of metallic elements (M1, M2, and M3), and the three types of metallic elements are any element of the RE element group selected in order. In an oxide system satisfying R(1)20 mol % and R(M2)60 mol % and R(M3)20 mol %, R(M1) being an average metallic element ratio of M1 in M1+M2+M3, SD(Ms)>0.15 is satisfied at a position at 50% of an average film thickness of a cross section including the c-axis, Ms being the metallic element of not larger of R(M1) and R(M3), SD(Ms) being a standard deviation/average value of a concentration of Ms.

A system includes a substrate having a high-temperature superconductor compound film disposed thereon. A first superconducting region is formed within the film and has a first stabilized oxygen content. A second superconducting region is also formed within the film and is located adjacent to the first superconducting region. The second superconducting region has a second stabilized oxygen content. A boundary region is formed within the film and separates the first superconducting region from the second superconducting region. A voltage source is connected to the first superconducting region and the second superconducting region. The boundary region emits electromagnetic radiation responsive to an applied voltage from the voltage source to one of the first superconducting region and the second superconducting region. A current flows from the first superconducting region to the second superconducting region, or vice versa, responsive to the applied voltage.