Magnetic Memory Device Using Domain Motion for Storage Capacity
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Solution Overview
Problem
Magnetic random access memories (MRAMs) face limitations in data storage capacity due to the ability to store only one bit of data per magnetic tunnel junction (MTJ) cell, necessitating a more efficient method for increasing information storage capacity.
Innovation Solution
A magnetic memory device with multiple memory tracks stacked on a substrate, each containing magnetic domains that represent data bits, utilizing magnetic domain motion and forming magnetic tunnel junction cells with a reference layer and non-magnetic tunneling barrier, along with selectors and input portions to facilitate data reading and writing operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If one bit of data is stored per MTJ cell using conventional MRAM architecture, then the device structure is simple and easy to manufacture, but the data storage capacity is limited
Solution Approach 1:
The patent transitions from a two-dimensional planar array to a three-dimensional stacked architecture by forming multiple memory tracks vertically above each other. Each memory track contains multiple magnetic domains that can store data bits, enabling increased storage capacity by utilizing the vertical dimension rather than only expanding horizontally.
Solution Approach 2:
The patent divides a single memory track into multiple discrete magnetic domains along the track length, where each domain can independently store a data bit. This segmentation allows multiple data bits to be stored within a single memory track, and combined with multiple stacked tracks, significantly increases overall storage capacity without proportionally increasing device footprint.
2Quantity of substance
If multiple data bits are stored per memory track using magnetic domain motion, then data storage capacity increases, but the complexity of data reading and writing operations increases
Solution Approach 1:
The patent replaces complex mechanical or multi-step electrical operations with magnetic domain motion driven by spin transfer torque. By applying a current through the MTJ cell, the magnetization direction of the free layer switches between parallel and anti-parallel states, automatically moving the magnetic domain boundary to encode data bits without requiring complex external control mechanisms.
Solution Approach 2:
The magnetic domain structure inherently provides the storage mechanism, where the position of domain walls naturally represents data bits. The system uses its own magnetic properties and spin-dependent conduction characteristics to perform both storage and readout functions, eliminating the need for separate mechanical actuators or complex control systems.
3Productivity
If magnetic domain motion is used to represent and move data bits, then data storage efficiency improves, but the precision of magnetic domain control must be high
Solution Approach 1:
The patent utilizes changes in magnetization direction (parallel vs. anti-parallel) as the fundamental parameter to represent binary data bits. By controlling the switching of magnetization states through spin transfer torque rather than requiring precise mechanical positioning, the system achieves high storage efficiency while reducing the precision requirements for domain control.
Solution Approach 2:
The patent exploits the phase transition-like behavior of magnetization switching in the free layer, where the magnetization direction abruptly changes between parallel and anti-parallel states relative to the pinned layer. This discrete state transition provides clear, distinguishable data states that are robust against control variations, reducing the need for extremely precise magnetic domain control.
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 configuration allows for increased data storage capacity by enabling multiple data bits to be stored in an array of magnetic domains, enhancing the efficiency of data storage and retrieval operations within the magnetic memory device.
Implementation Method 1
MRAM may use giant magnetoresistance (GMR) and/or tunnel magnetoresistance (TMR) because spin, which is a degree of freedom of an electron, may have a significant influence on electron delivery
Implementation Method 2
TMR is resistance where a current may more easily flow when two ferromagnetic materials have a same magnetization direction in an adjoining arrangement of ferromagnetic material/insulator/ferromagnetic materials than if the two ferromagnetic materials have different magnetization directions
Implementation Method 3
MRAM is a solid state magnetic memory that uses magnetic resistance due to a spin-dependent conduction characteristic of a nano magnetic material
Data Source
AI summary
Example embodiments may provide a magnetic memory device. The example embodiment magnetic memory devices may include a plurality of memory tracks, bit lines, connectors, a first input portion, and/or selectors. The memory track(s) may be stacked on a substrate to form a multi-stack. A plurality of magnetic domains may be formed in the memory track so that a data bit may be represented by a magnetic domain and may be stored in an array. The bit line(s) may be formed along respective memory tracks. The connector(s) may form a magnetic tunnel junction (MTJ) cell with one data bit region of the memory track. The first input portion may be electrically connected to each memory track and may input a magnetic domain motion signal to move data stored on a data bit region of the memory track to an adjoining data bit region. The selector(s) may select a memory track from a plurality of memory tracks on which a reading and/or writing operation may to be performed.