Magnetically Stabilized Josephson Junction Memory Cell
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current superconducting digital technologies lack effective random-access memory (RAM) with adequate capacity and speed for high-end and quantum computing applications, and existing hybrid memory solutions suffer from high power dissipation and integration density limitations.
Innovation Solution
A magnetically stabilized magnetic Josephson junction memory cell is developed, incorporating a magnetic Josephson junction stack with a magnetically stabilizing structure to pin the magnetic reference layer, reducing the impact of stray flux and allowing high critical currents, while maintaining integration density and reducing power dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a magnetic Josephson junction is used for superconducting memory, then high speed and low power dissipation are achieved, but stray flux causes false switching between logical states
Solution Approach 1:
An antiferromagnetic layer is introduced as an intermediary between the magnetic layers in the Josephson junction. This layer mediates the magnetic interaction by providing exchange coupling that stabilizes the relative magnetic orientation, thereby preventing stray flux from causing false switching while maintaining the desired logical states.
Solution Approach 2:
The magnetic Josephson junction is constructed as a composite structure with multiple layers including ferromagnetic layers, nonmagnetic spacer layers, and antiferromagnetic layers. This composite material architecture combines the beneficial properties of each material type to achieve both high-speed operation and immunity to stray flux interference.
2Reliability
If the magnetic reference layer is made stable against stray flux, then false switching is reduced, but the critical current of the junction decreases
Solution Approach 1:
The stability against stray flux is achieved locally at the interfaces between magnetic layers and antiferromagnetic layers, where exchange coupling occurs. The bulk regions of the magnetic layers maintain their full magnetic moment and contribute to the critical current, thus achieving both stability and high current capability through spatially differentiated properties.
Solution Approach 2:
The thickness of the antiferromagnetic layer and the strength of exchange coupling are optimized to achieve the desired balance between stability and critical current. By adjusting these parameters, the system achieves sufficient pinning of the magnetic reference layer while maintaining adequate supercurrent flow through the junction.
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 provides a stable and high-performance memory cell capable of operating at cryogenic temperatures with reduced power consumption and increased integration density, addressing the limitations of existing superconducting memory technologies.
Implementation Method 1
The magnetic stabilizing structure magnetically couples with the magnetic reference layer to strengthen the fixed state of the magnetic reference layer
Implementation Method 2
JMRAM relies on the oscillation of the relative Cooper pair phase with magnetic layer thickness to produce junctions that exhibit a Josephson phase of either zero or π radians
Implementation Method 3
superconducting memory elements capable of writing and reading a logical '0' or logical '1' state... on an integrated circuit (IC) chip that can be cooled to superconducting temperatures (e.g., about four kelvins or less)
Data Source
AI summary
A memory cell is provided that comprises a first superconductor electrode, a second superconductor electrode, and a magnetic Josephson junction (MJJ) stack disposed between the first superconductor electrode and the second superconductor electrode. The MJJ stack includes a magnetic reference layer and a magnetic storage layer. The memory cell further comprises a magnetically stabilizing structure disposed between the MJJ stack and the second superconductor electrode, wherein the magnetic stabilizing structure magnetically couples with the magnetic reference layer to strengthen the fixed state of the magnetic reference layer.