Voltage Controlled Magnetic Random Memory Unit
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Solution Overview
Problem
Magnetic memory devices require external magnetic fields for operation, limiting integration and development in information technology, and existing technologies struggle to control magnetization direction during writing, affecting reading and writing processes.
Innovation Solution
A voltage-controlled magnetic random memory unit is developed, comprising a ferroelectric layer, a spin-orbit coupling layer, and a magnetic layer, where voltages applied to these layers induce directional switching of magnetization and spin currents, allowing for independent control of reading and writing without external magnetic fields, using a multilayer structure that includes a non-magnetic intermediate and antiferromagnetic layers for resistance change detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external magnetic fields are used for magnetic memory operation, then magnetization switching can be achieved, but device integration is limited and complexity increases
Solution Approach 1:
The patent replaces the mechanical/external magnetic field system with an electric field system. Specifically, it uses spin-orbit coupling effect where an electric current applied to the spin-orbit coupling layer generates a spin current that exerts torque on the magnetic layer, achieving magnetization switching through electrical means rather than external magnetic fields. This substitution enables better device integration and reduces complexity.
Solution Approach 2:
The patent introduces a spin-orbit coupling layer as an intermediary between the electrical input and the magnetic layer. This intermediate layer converts the electrical current into spin current through the spin-orbit coupling effect, which then acts on the magnetic layer to achieve magnetization switching. This intermediary mechanism enables controlled magnetization switching without requiring external magnetic fields.
2Reliability
If spin transfer torque effect is used for writing, then magnetization switching can be achieved, but reading and writing affect each other due to single channel operation
Solution Approach 1:
The patent transitions from single-channel operation to multi-channel operation by utilizing different spatial dimensions. The writing current flows laterally through the spin-orbit coupling layer, while the reading current flows perpendicularly through the magnetic tunnel junction. This dimensional separation allows independent reading and writing operations without mutual interference, as each operation uses a different current path and channel.
3Ease of operation
If electrical writing is realized by spin-orbit coupling effect, then reading and writing can be implemented on different channels, but magnetization direction cannot be controlled during writing
Solution Approach 1:
The patent merges two effects: the spin-orbit coupling effect for generating spin current and the ferroelectric effect for directional control. The ferroelectric layer's polarization direction controls the orientation of the spin current from the spin-orbit coupling layer, thereby controlling the magnetization switching direction. This combination allows both channel independence and directional control to be achieved simultaneously.
Solution Approach 2:
The patent uses the ferroelectric layer's polarization state as a controllable parameter to regulate the magnetization switching direction. By changing the polarization direction of the ferroelectric layer (which can be switched between up and down states), the direction of the spin current and consequently the magnetization switching direction is controlled. This parameter change mechanism enables adaptable magnetization control while maintaining electrical writing capability.
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
Enables controlled and programmable magnetization switching, allowing for XOR gate logic implementation and various logic functions, improving computational efficiency and logic device density, while enabling information storage and processing without external magnetic fields.
Implementation Method 1
In addition to the spin transfer torque effect, the electrical writing can also be realized by the spin-orbit coupling effect
Implementation Method 2
a spin-orbit coupling layer located above the ferroelectric layer and applied with a second voltage to produce a spin current in a direction perpendicular to the spin-orbit coupling layer
Implementation Method 3
the resistance change, as output information, is detected from the output by means of the magnetoresistance effect
Implementation Method 4
an anomalous Hall voltage is detected from the output
Data Source
AI summary
A voltage controlled magnetic random memory unit, a memory, and a logic device thereof. The memory unit includes: a ferroelectric layer applied with a first positive or negative voltage to control a directional switching of magnetization; a spin-orbit coupling layer located above the ferroelectric layer and applied with a second voltage to produce a spin current in a direction perpendicular to the spin-orbit coupling layer; a first magnetic layer located above the spin-orbit coupling layer, wherein, the spin current induces a random up and down magnetic switching of the first magnetic layer. The spin current may induce a directional switching of the first magnetic layer in conjunction with the first voltage applied to the ferroelectric layer. The invention generates ferroelectric polarization by applying a voltage to both ends of the ferroelectric layer, thereby generating a non-uniform spin-orbit coupling effect, which can modulate the direction in which the current induces the magnetic switching of the magnetic film.