Magnetic Memory Cell Inverse Field Threshold Current
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The magnetic memory cell faces challenges in achieving stable operation for both '0' and '1' writing due to high threshold magnetization switching currents, especially when the magnetoresistance effect element is in the antiparallel state, leading to difficulties in meeting the necessary current conditions for writing from the parallel to antiparallel state.
Innovation Solution
The introduction of an effective magnetic field applied in the inverse direction of the pinned layer's magnetization direction to the recording layer, optimizing the conditions for the magnetic field to reduce the threshold current and ensure stable operation, which does not require changing the magnetic field direction based on the information being written.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a voltage is applied to write '1' (transition from parallel to antiparallel state), then the magnetization switching occurs, but the threshold current becomes excessively high making stable operation difficult
Solution Approach 1:
An effective magnetic field Hex is applied to the recording layer in advance (before the write operation) to reduce the threshold magnetization switching current. This preliminary action modifies the magnetic energy landscape, creating an energy barrier reduction that enables lower current to achieve the same switching effect, thereby resolving the contradiction between reliable switching and excessive current requirements
Solution Approach 2:
The patent changes the magnetic field parameter by applying an effective magnetic field Hex in the inverse direction of the pinned layer's magnetization. This parameter change (adding a DC magnetic field component) modifies the switching characteristics of the magnetoresistance effect element, reducing the threshold current for '1' writing while maintaining stable operation for both '0' and '1' states
2Quantity of substance
If the magnetoresistance effect element is miniaturized to increase storage density, then more data can be stored, but the threshold current becomes even higher relative to available drive current
Solution Approach 1:
The effective magnetic field Hex is applied as a preliminary measure to reduce the threshold current before miniaturization effects become critical. This allows the magnetoresistance effect element to be scaled down while maintaining acceptable switching currents, enabling increased storage density without proportionally increasing the threshold current problem
Solution Approach 2:
By changing the magnetic field parameter (applying Hex), the patent compensates for the increased threshold current that naturally occurs with miniaturization. This parameter modification enables smaller device dimensions while maintaining the drive current margin necessary for reliable operation
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 stable operation for both '0' and '1' writing in magnetic random access memory (MRAM) by optimizing the effective magnetic field conditions, addressing the issue of high threshold currents and ensuring reliable data storage despite miniaturization.
Implementation Method 1
The magnetoresistance effect element 101 has a base structure comprising 3 layers in which a nonmagnetic layer 108 is sandwiched between two ferromagnetic layers 106, 107... The magnetoresistance effect element 101 has a low resistance when the magnetization directions of the two ferromagnetic layers 106, 107 are in parallel with each other (P state). The magnetoresistance effect element 101 has a high resistance when the magnetization directions of the two ferromagnetic layers 106, 107 are in antiparallel with each other (AP state).
Implementation Method 2
Bit information is written by spin-transfer torque magnetization switching by current flowing through the magnetoresistance effect element 101. When a current flows from the pinned layer to the recording layer, magnetization of the recording layer becomes antiparallel with the magnetization of the pinned layer, and bit information becomes '1'. When a current flows from the recording layer to the pinned layer, the magnetization of the recording layer becomes parallel with the magnetization of the pinned layer, and the bit information becomes '0'. Since the velocity of the magnetization switching by the current is 1 nanosecond or so, MRAM can perform writing with extremely high speed.
Implementation Method 3
The introduction of an effective magnetic field applied in the inverse direction of the pinned layer's magnetization direction to the recording layer, optimizing the conditions for the magnetic field to reduce the threshold current and ensure stable operation
Data Source
AI summary
A relation between a drive current of a selection transistor of a magnetic memory and a threshold magnetization switching current of the magnetoresistance effect element is optimized. In order to optimize the relation between the drive current of the selection transistor and the threshold magnetization switching current of the magnetoresistance effect element 101 of the magnetic memory cell, a mechanism 601-604 for dropping the threshold magnetization switching current on “1” writing is provided that applies a magnetic field that is in the inverse direction of the pinned layer to the recording layer of the magnetoresistance effect element.