Voltage-Driven Shift Register Magnetic Memory Design

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Solution Overview

Problem

Shift register type magnetic memories face challenges in achieving large capacity due to increased physical length, leading to malfunction risks from unsharpened current pulse waveforms caused by capacitance or inductance components, and require high current densities and voltages, which hinder efficient information shifting.

Innovation Solution

The design incorporates a magnetic nanowire with alternating first and second control electrodes, where voltage is alternately applied to shift magnetic domain walls, allowing for stable and reversible shift operations with low power consumption, even with hundreds of digits, by using voltage application instead of current pulses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the physical length of the shift register is increased to achieve large capacity memory, then the memory capacity is improved, but the current pulse waveform becomes unsharpened due to capacitance or inductance components, increasing malfunction probability

Engineering Contradiction:

Improvememory capacityVSAvoidshift operation reliability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent replaces the conventional current pulse-driven magnetic domain wall shifting mechanism with a voltage-driven mechanism. By applying voltage to control electrodes positioned adjacent to the magnetic nanowire, the system generates an electric field that directly influences the magnetic domain wall motion, eliminating the need for current pulses and thereby avoiding waveform degradation issues associated with long physical lengths.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention changes the fundamental operating parameter from current to voltage. Instead of using current pulses that suffer from capacitance and inductance effects in long structures, the system uses voltage application to control electrodes, which generates the necessary electric field for domain wall motion without the same electrical degradation problems.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If a large current density is applied to drive magnetic domain in a shift register with 100 digits or more, then the shift operation can be performed, but the resistance value increases due to increased magnetic nanowire length, requiring high voltage

Engineering Contradiction:

Improveshift operation efficiencyVSAvoidpower consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent substitutes the current-driven mechanism with a voltage-driven mechanism through control electrodes. This eliminates the need for large current densities to overcome resistance in long magnetic nanowires, as the voltage applied to the control electrodes generates an electric field that facilitates domain wall motion more efficiently.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The control electrodes act as intermediaries between the voltage source and the magnetic nanowire. By positioning electrodes adjacent to the nanowire and applying voltage to them, the system creates a localized electric field that interacts with the magnetic domain walls, enabling efficient shifting without requiring direct high-current injection through the entire length of the nanowire.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

This approach enables a highly reliable and densely packed shift register type magnetic memory with low power consumption and stable operation, avoiding the limitations of traditional current pulse-driven systems.

Implementation Method 1

each having a magnetization direction

Methodology Applied

Scientific EffectMagnetization: Magnetism

Implementation Method 2

a first control electrode group and a second control electrode group arranged with the magnetic nanowire being sandwiched therebetween

Methodology Applied

Scientific EffectElectric field: Electric Field

Data Source

PatentUS9190167B2Shift register and shift register type magnetic memory

Publication Date: 2015.11.17 KIOXIA CORP

AI summary

A shift register according to an embodiment includes: a magnetic nanowire; a first control electrode group and a second control electrode group arranged with the magnetic nanowire being sandwiched therebetween, the first control electrode group including a plurality of first control electrodes arranged to be spaced apart from each other along a direction in which the magnetic nanowire extends, the second control electrode group including a plurality of second control electrodes arranged to be spaced apart from each other to correspond to the plurality of first control electrodes along the direction in which the magnetic nanowire extends, and the second control electrodes corresponding to the first control electrodes being shifted in the direction in which the magnetic nanowire extends; a first driving unit for driving the first control electrode group; and a second driving unit for driving the second control electrode group.