REBCO Barrier Layer Blocks Leak Current in Josephson Junctions
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Solution Overview
Problem
Conventional joined bodies with Josephson junctions experience leak currents due to yttrium diffusion from superconducting layers into non-superconducting layers, leading to incomplete superconductivity and impaired Josephson effects.
Innovation Solution
A joined body with a barrier layer of REBCO material, where the rare earth elements in the superconducting layers are selected to exhibit superconductivity and those in the barrier layer are chosen to prevent superconductivity, effectively blocking leak currents by controlling the crystal orientation and composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a non-superconducting layer is used as a barrier layer, then the structure is simple and manufacturing is easier, but yttrium diffusion occurs causing leak currents and incomplete superconductivity
Solution Approach 1:
The patent changes the material composition parameter of the barrier layer from conventional non-superconducting materials to REBCO material with specific rare earth elements (Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu) that have atomic radii within 0.12-0.16 nm. This parameter change prevents yttrium diffusion while maintaining superconductivity, thereby improving reliability without significantly complicating manufacturing
Solution Approach 2:
The patent uses a composite approach by selecting specific rare earth elements with appropriate atomic radii to create a barrier layer that combines both barrier functionality and superconducting properties. The REBCO material with specifically selected rare earth elements serves as a composite solution that addresses both the barrier requirement and the superconductivity requirement simultaneously
2Reliability
If the barrier layer is made of REBCO material, then leak currents are blocked and superconductivity is maintained, but the manufacturing process becomes more complex
Solution Approach 1:
The patent simplifies the device complexity by changing the key parameter of rare earth element selection based on atomic radius. By specifying elements with atomic radii of 0.12-0.16 nm, the patent creates a systematic criterion for material selection that, while precise, follows a clear pattern rather than requiring complex multi-layer structures or intricate device designs
3Manufacturing precision
If conventional epitaxial growth is used, then the Josephson junction is formed, but yttrium diffusion into the barrier layer causes pinholes and leak currents
Solution Approach 1:
The patent applies preliminary anti-action by pre-selecting rare earth elements with specific atomic radii (0.12-0.16 nm) for the barrier layer before the epitaxial growth process begins. This preliminary selection creates inherent resistance to yttrium diffusion during the subsequent manufacturing process, preventing pinhole formation and leak currents before they can occur
Solution Approach 2:
The patent changes the material parameter of the barrier layer from conventional non-superconducting materials to REBCO materials with specifically selected rare earth elements. This parameter change fundamentally alters the diffusion characteristics during epitaxial growth, preventing yttrium from diffusing into the barrier layer and forming pinholes, thereby eliminating the harmful effects while maintaining manufacturing precision
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively blocks leak currents between superconducting layers, maintaining the integrity of the Josephson junction and ensuring the Josephson effect is exhibited without pinholes, while also shortening the heat treatment time by forming a liquid phase in the fine crystal layer.
Implementation Method 1
heating the first substrate and the second substrate in a state where the first substrate and the second substrate are held so that the fine crystal layer is sandwiched between the first superconducting layer and the second superconducting layer
Implementation Method 2
The first superconducting layer, the barrier layer, and the second superconducting layer are formed of a REBCO. A leak current from one of the first superconducting layer and the second superconducting layer to the other of the first superconducting layer and the second superconducting layer is blocked by the barrier layer
Data Source
AI summary
A joined body includes: a first superconducting layer, a barrier layer arranged on the first superconducting layer, and a second superconducting layer arranged on the barrier layer. The first superconducting layer, the barrier layer, and the second superconducting layer are formed of a REBCO. A leak current from one of the first superconducting layer and the second superconducting layer to the other of the first superconducting layer and the second superconducting layer is blocked by the barrier layer.