Voltage-Controlled Magnetic Memory with Schottky Barriers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional spin transfer torque magnetization switching methods for magnetic random access memories require high current densities, leading to increased power consumption, larger circuit sizes, and higher cell selection transistor areas, while voltage-controlled writing methods face challenges in reading resistance values due to the presence of insulating films.
Innovation Solution
A magnetic memory design incorporating a multilayer structure with a semiconductor layer, ferromagnetic layers, and a voltage applying unit, allowing for voltage-controlled writing and reading by manipulating the magnetization direction without current flow through the use of Schottky barriers and high dielectric materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If voltage-controlled writing method is used, then power consumption is reduced, but resistance cannot be read due to insulating film blocking current
Solution Approach 1:
The patent divides the memory structure into separate functional regions: a first region with an insulating film for voltage-controlled writing, and a second region without insulating film for resistance reading. This segmentation allows each region to serve its specific function independently, resolving the contradiction between voltage-controlled writing and resistance reading capabilities
Solution Approach 2:
The patent introduces a nonmagnetic metal layer as an intermediary between the ferromagnetic layers, which serves as a tunnel barrier for spin-polarized current while allowing resistance modulation. This intermediary enables both voltage-controlled writing through spin transfer torque and resistance reading through tunneling current, eliminating the need for separate insulating films
2Speed
If spin transfer torque magnetization switching is used, then writing speed is improved, but current density requirement increases leading to larger circuit size
Solution Approach 1:
The patent changes the writing mechanism from current-controlled spin transfer torque to voltage-controlled magnetization switching. By applying voltage pulses that induce spin-polarized current through spin-orbit coupling in the ferromagnetic layer, the system achieves fast writing speeds with significantly reduced current density requirements, thereby reducing circuit size
Solution Approach 2:
The patent replaces the conventional current-controlled writing mechanism with a voltage-controlled mechanism based on spin-orbit coupling. This substitution eliminates the need for high current densities and complex current control circuits, reducing the overall circuit area while maintaining fast writing speeds
3Use of energy by moving object
If insulating film is added for voltage-controlled writing, then power consumption decreases, but device complexity increases
Solution Approach 1:
The patent designs the ferromagnetic layer to serve multiple functions: it acts as both the magnetic storage medium and the active element for voltage-controlled writing through spin-orbit coupling. The nonmagnetic metal layer also serves dual purposes as a tunnel barrier and a current path for resistance reading, reducing the need for separate dedicated components and simplifying the overall structure
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 lower power consumption and compact memory arrays with voltage-controlled writing and reading capabilities, addressing the limitations of current methods by maintaining magnetization direction changes without current flow and improving writing efficiency.
Implementation Method 1
The voltage-controlled writing applies a voltage to the magnetization storage layer of the magnetoresistive element via an insulating film to change the number of electrons in the magnetization storage layer near the interface with the insulating film, thereby switching the magnetization direction of the magnetization storage layer
Implementation Method 2
allowing for voltage-controlled writing and reading by manipulating the magnetization direction without current flow through the use of Schottky barriers and high dielectric materials
Implementation Method 3
a magnetoresistive element with a tunnel magnetoresistance effect as a storage element in a magnetic random access memory
Data Source
AI summary
A magnetic memory according to an embodiment includes: a multilayer structure including a semiconductor layer and a first ferromagnetic layer; a first wiring line electrically connected to the semiconductor layer; a second wiring line electrically connected to the first ferromagnetic layer; and a voltage applying unit electrically connected between the first wiring line and the second wiring line to apply a first voltage between the semiconductor layer and the first ferromagnetic layer during a write operation, a magnetization direction of the first ferromagnetic layer being switchable by applying the first voltage.