Racetrack Memory Josephson Supercurrent Diode Reading Element
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Solution Overview
Problem
Current racetrack memory devices face challenges in reading data efficiently at low temperatures and high speeds while minimizing energy consumption, particularly due to limitations in existing reading elements, and there is a need for technologies that can operate effectively in quantum computing applications where high-frequency signals and large numbers of qubits are required.
Innovation Solution
A racetrack memory device utilizing a polarity-reversible Josephson supercurrent diode, where the Josephson Junction is magnetized by the magnetic regions of a racetrack, allowing for the detection of magnetic domains and domain walls using a Pt layer or Pt-alloy layer that is proximity-magnetized by a ferrimagnetic material, enabling efficient data reading and domain manipulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional reading elements are used in racetrack memory, then device complexity is reduced, but read-out speed and energy efficiency deteriorate
Solution Approach 1:
The patent changes the fundamental operating parameters of the reading element by using a Josephson junction that operates in the superconducting regime with critical currents in the microampere range, enabling ultrafast switching and read-out operations at speeds exceeding 1 GHz while maintaining low energy consumption per operation
Solution Approach 2:
The reading element employs a composite structure combining superconducting materials (for the Josephson junction electrodes), magnetic materials (for the racetrack and domain wall manipulation), and insulating barriers (for the Josephson junction formation), creating a multi-material system that achieves both high speed and low energy operation
2Use of energy by moving object
If superconducting materials are used to increase read-out speed, then energy consumption decreases, but device complexity increases
Solution Approach 1:
The Josephson junction utilizes the inherent quantum mechanical properties of superconducting materials to achieve low-energy operation without requiring external energy input for maintaining the superconducting state, as the supercurrent flows without resistance and dissipates minimal energy during read-out operations
Solution Approach 2:
The patent replaces conventional resistive or magnetic reading mechanisms with a quantum-mechanical Josephson effect-based system, where the reading operation is performed through quantum tunneling of Cooper pairs across the Josephson junction, eliminating the need for high-power electrical signals and reducing energy consumption
3Measurement precision
If polarity-reversible Josephson supercurrent diode is used, then measurement precision of domain walls improves, but device complexity increases
Solution Approach 1:
The patent introduces asymmetry into the Josephson junction by creating a polarity-reversible supercurrent diode effect through the integration of chiral domain walls with the junction structure, where the domain wall polarity (head-to-head or tail-to-tail) asymmetrically modulates the supercurrent flow, enabling precise detection of domain wall position and polarity through current direction measurements
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 enables high-speed data reading with low energy consumption and supports the operation of quantum computers by allowing for the reliable detection and manipulation of domain walls, enhancing the scalability and performance of racetrack memory devices.
Implementation Method 1
One of the most interesting phenomena in superconductivity is the Josephson effect. The Josephson effect produces a current, known as a supercurrent that flows continuously without any voltage applied, across a device known as a Josephson junction (JJ).
Implementation Method 2
A JJ reading element magnetized by the magnetic regions of a racetrack and comprising two or more superconducting electrodes, which are separated by an ultrathin crystalline Pt layer or Pt-alloy layer.
Data Source
Figure 1a~2d
Figure 3a~3d
Figure 4a~4f
AI summary
The present disclosure relates to a Racetrack (RT) memory, comprising a racetrack layer and at least one reading element, wherein the reading element comprises a polarity-reversible Josephson supercurrent diode (= JJ).