Spin Current Assisted Magnetoresistance Device for Low-Current Writing
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Solution Overview
Problem
Magnetization reversal in TMR elements using spin transfer torque (STT) has high inversion current density and time delays, which can lead to reduced element life and writing efficiency, especially as element sizes decrease.
Innovation Solution
A spin current assisted magnetoresistance effect device that combines STT and spin-orbit torque (SOT) effects by merging or dividing inversion currents in a controlled manner to reduce current density and time required for magnetization reversal, utilizing a spin-orbit torque wiring intersecting the magnetoresistance effect element and controlling the application of STT and SOT inversion currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spin transfer torque (STT) is used for magnetization reversal, then magnetization reversal can be achieved, but high inversion current density is required which reduces element life
Solution Approach 1:
The patent combines STT and SOT methods into a hybrid system where a first current path carries current through the magnetoresistance effect element for STT, while a second current path carries current through a spin-orbit torque wiring for SOT. The two torques work together to reverse magnetization, allowing lower current density in the element while maintaining effective magnetization reversal.
Solution Approach 2:
The spin-orbit torque wiring acts as an intermediary that converts charge current into pure spin current via the spin Hall effect. This pure spin current then acts on the ferromagnetic layer to assist magnetization reversal, reducing the burden on the magnetoresistance effect element and lowering the required inversion current density.
2Productivity
If spin transfer torque (STT) is used for magnetization reversal, then magnetization reversal can be achieved, but time delay occurs until magnetization reversal occurs after application of inversion current
Solution Approach 1:
The patent merges STT and SOT mechanisms to overcome the time delay limitation of STT alone. The SOT component provides an additional torque that acts more rapidly on the magnetization, reducing the overall time required for magnetization reversal and improving writing speed.
3Area of moving object
If element size is decreased, then more elements can be integrated, but current that can flow through thin wiring is limited which prevents appropriate writing
Solution Approach 1:
The patent segments the current paths into two separate routes: one through the magnetoresistance effect element and another through the spin-orbit torque wiring. This segmentation allows the heavy current load to be borne by the dedicated spin-orbit torque wiring rather than the thin interconnects, enabling continued scaling to smaller element sizes.
4Reliability
If pure spin current is used for magnetization reversal, then current flowing through MR element is zero extending element life, but higher current density is required to generate sufficient pure spin current
Solution Approach 1:
The patent merges pure spin current from SOT with spin-polarized current from STT to achieve magnetization reversal. This combination allows the system to benefit from the low stress on the element provided by pure spin current while supplementing it with the efficient spin transfer torque, reducing the required current density in the spin-orbit torque wiring compared to using SOT alone.
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 device achieves high writing speed and reduced current density for magnetization reversal, potentially extending the life of the magnetoresistance effect element by leveraging the SOT effect to assist magnetization reversal with lower energy consumption and faster recording times.
Implementation Method 1
it has been proposed that magnetization reversal using a pure spin current generated in accordance with a spin-orbit interaction could be applied
Implementation Method 2
A pure spin current that has undergone spin-orbit-interaction induces a spin-orbit torque (SOT) and causes magnetization reversal in accordance with the SOT
Implementation Method 3
a system performing writing (magnetization reversal) using a spin transfer torque (STT) generated by causing a current to flow in a lamination direction of a magnetoresistance element
Implementation Method 4
a giant magnetoresistance (GMR) element formed by a multi-layered film with a ferromagnetic layer and a nonmagnetic layer
Implementation Method 5
a tunnel magnetoresistance (TMR) element using an insulating layer (a tunnel barrier layer or a barrier layer) as a nonmagnetic layer
Data Source
AI summary
A spin current assisted magnetoresistance effect device includes: a spin current assisted magnetoresistance effect element including a magnetoresistance effect element part and a spin-orbit torque wiring; and a controller electrically connected to the spin current assisted magnetoresistance effect element. In a portion in which the magnetoresistance effect element part and the spin-orbit torque wiring are bonded, an STT inversion current flowing through the magnetoresistance effect element part and an SOT inversion current flowing through the spin-orbit torque wiring merge or are divided, and the controller is configured to be capable of performing control for applying the STT inversion current to the spin current assisted magnetoresistance effect element at the same time as an application of the SOT inversion current or a time application of the SOT inversion current.