SOT-MRAM Cell with Ferroelectric Heterostructure for Deterministic Switching
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Solution Overview
Problem
Existing spin-orbit torque (SOT) based magnetic random access memory (MRAM) devices cannot achieve deterministic magnetization inversion without an applied magnetic field, which limits their integration and stability, and are not compatible with existing CMOS processes.
Innovation Solution
A spintronic device with a ferroelectric/ferromagnetic heterostructure and a magnetic tunnel junction, where the ferroelectric/ferromagnetic heterostructure includes a multiferroic material layer and a ferromagnetic layer, and a heavy metal layer is used between the ferroelectric/ferromagnetic heterostructure and the magnetic tunnel junction, enabling deterministic magnetization inversion through interface magnetic fields generated by electric field control, eliminating the need for an external magnetic field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If spin-orbit torque is used to reverse magnetic free layer, then magnetization inversion speed increases and critical current density decreases, but deterministic directional magnetization inversion cannot be achieved without applied magnetic field
Solution Approach 1:
The patent introduces perpendicular magnetic anisotropy to break the symmetry of the magnetic free layer. By engineering the magnetic anisotropy energy landscape, the system achieves deterministic magnetization switching without requiring external magnetic fields, thus resolving the contradiction between fast inversion speed and reliable directional control
Solution Approach 2:
The patent modifies the magnetic anisotropy parameters of the magnetic free layer through material composition control and interface engineering. By changing the perpendicular magnetic anisotropy strength, the system enables deterministic magnetization inversion while maintaining fast switching speeds, eliminating the need for applied magnetic fields
2Reliability
If applied magnetic field is introduced to achieve deterministic magnetization inversion, then magnetization inversion becomes deterministic, but device complexity increases and integration becomes difficult
Solution Approach 1:
The patent extracts and eliminates the external magnetic field component from the system. By embedding the necessary magnetic anisotropy directly into the magnetic free layer through material design, the system achieves deterministic magnetization inversion without requiring external magnetic field generation circuits, thus reducing device complexity and enabling better integration
Solution Approach 2:
The patent introduces perpendicular magnetic anisotropy as an intermediary mechanism that mediates between the spin-orbit torque and the magnetization state. This anisotropy acts as an internal field that enables deterministic switching without requiring external magnetic fields, thereby simplifying the overall device structure
3Power
If large current is passed through magnetic tunnel junction for information writing, then magnetization inversion is achieved, but energy consumption increases and device stability deteriorates
Solution Approach 1:
The patent replaces the conventional spin transfer torque mechanism (which requires current through the junction) with spin-orbit torque mechanism. By using the spin Hall effect in adjacent ferromagnetic metal layers, the system achieves magnetization inversion through spin current generated in the adjacent layer, eliminating the need for high current through the magnetic tunnel junction and thereby reducing energy consumption and improving stability
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 allows for deterministic magnetization inversion with low critical current density and high data write rate, improving device stability and compatibility with existing CMOS technology, facilitating large-scale manufacturing and integration.
Implementation Method 1
interface magnetic fields generated by electric field control
Implementation Method 2
when the Spin-Orbit Torque (SOT, Spin-Orbit Torque) effect is used to reverse a magnetic free layer
Implementation Method 3
Magnetic Random Access Memory (MRAM) based on Magnetic Tunnel Junction (MTJ)
Data Source
AI summary
The disclosure provides a spintronic device, a SOT-MRAM storage cell, a storage array and a in-memory computing circuit. The spintronic device includes a ferroelectric/ferromagnetic heterostructure, a magnetic tunnel junction, and a heavy metal layer between the ferroelectric/ferromagnetic heterostructure and the magnetic tunnel junction; the ferroelectric/ferromagnetic heterostructure includes a multiferroic material layer and a ferromagnetic layer arranged in a stacked manner, and the magnetic tunnel junction includes a free layer, an insulating layer and a reference layer arranged in a stacked manner, and the heavy metal layer is disposed between the ferromagnetic layer and the free layer. According to one or more embodiments of the disclosure, the spintronic device, the SOT-MRAM storage cell, the storage array and the in-memory computing circuit can realize deterministic magnetization inversion under the condition of no applied field assistance.