Dual Magnetic Junctions with Spin-Orbit Torque for Low Error Rates
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Solution Overview
Problem
Conventional spin transfer torque based magnetic memories face challenges with high write error rates and reduced spin-transfer torque amplitude at shorter write current pulses, leading to increased energy consumption and reduced data rates.
Innovation Solution
Incorporating a spin-orbit interaction (SO) active layer adjacent to the reference layer in dual magnetic junctions, which exerts a spin-orbit torque on the reference layer due to an in-plane current, allowing for faster switching and reduced write error rates by enhancing the spin-transfer torque efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional spin transfer torque based switching is used in dual magnetic tunneling junctions, then the magnetic memory can store information with non-volatility and excellent endurance, but the write error rate increases and spin-transfer torque amplitude decreases at shorter write current pulses
Solution Approach 1:
The patent introduces a spin-orbit interaction active layer as an intermediary component between the current path and the reference layer. This layer mediates the interaction by converting charge current into spin-orbit torque, which then acts on the reference layer to enable switching. This intermediary mechanism resolves the contradiction by providing an alternative torque generation pathway that is less susceptible to pulse width limitations.
Solution Approach 2:
The patent changes the physical mechanism parameter from pure spin transfer torque to spin-orbit interaction based torque. This parameter change allows the system to operate effectively at shorter pulse widths by utilizing the different physical characteristics of spin-orbit coupling, which provides stronger and faster torque generation compared to conventional spin transfer mechanisms.
2Productivity
If the duration of write current pulses is reduced to increase data rates, then the switching speed improves, but the spin-transfer torque amplitude decreases leading to higher write error rates
Solution Approach 1:
The patent replaces the conventional spin transfer torque mechanism with a spin-orbit interaction based mechanism. This substitution fundamentally changes how torque is generated and applied, allowing for effective switching at shorter pulse durations. The spin-orbit interaction provides a more efficient coupling between charge current and magnetic moment, maintaining sufficient torque amplitude even at reduced pulse widths required for high data rates.
3Ease of manufacture
If conventional magnetic junctions are used with current-perpendicular-to-plane current driving, then the structure is simple and manufacturing is easier, but the spin transfer torque efficiency is limited
Solution Approach 1:
The patent employs a composite structure combining conventional magnetic layers with a spin-orbit interaction active layer. This composite approach integrates the manufacturing simplicity of conventional CPP-based magnetic junctions with the enhanced torque efficiency of spin-orbit interaction materials. The composite structure allows standard fabrication processes to be used while incorporating materials with strong spin-orbit coupling to improve overall torque efficiency.
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 use of spin-orbit interaction in dual magnetic junctions improves write time and reduces write error rates, enabling lower switching currents and higher magnetoresistance, thus enhancing the performance and reliability of magnetic memories.
Implementation Method 1
at least one spin-orbit interaction (SO) active layer... configured to exert a SO torque on the first reference layer due to a current passing through the at least one SO active layer
Implementation Method 2
A spin polarized current driven through the magnetic junction exerts a spin torque on the magnetic moments in the magnetic junction
Implementation Method 3
enhancing the spin-transfer torque efficiency... higher magnetoresistance
Data Source
AI summary
A magnetic memory is described. The magnetic memory includes dual magnetic junctions and spin-orbit interaction (SO) active layer(s). Each dual magnetic junction includes first and second reference layers, first and second nonmagnetic spacer layers and a free layer. The free layer is magnetic and between the nonmagnetic spacer layers. The nonmagnetic spacer layers are between the corresponding reference layers and the free layer. The SO active layer(s) are adjacent to the first reference layer of each dual magnetic junction. The SO active layer(s) exert a SO torque on the first reference layer due to a current passing through the SO active layer(s) substantially perpendicular to a direction between the SO active layer(s) and the first reference layer. The first reference layer has a magnetic moment changeable by at least the SO torque. The free layer is switchable using a spin transfer write current driven through the dual magnetic junction.