Perovskite Nitride Magnetic Memory Cells for Stable MRAM Switching
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Solution Overview
Problem
Existing MRAM technologies face challenges such as high-power consumption, limited thermal stability, and scalability due to high switching current densities, thermal sensitivity, and sensitivity to external magnetic fields, which hinder their widespread adoption.
Innovation Solution
A magnetic device with a tri-layer structure comprising perovskite-based nitride materials, including a spacer layer and magnetic electrode layers with a shared lattice structure, which maintains high spin polarization and magnetoresistance through controlled composition and lattice matching, reducing lattice disorder and enhancing thermal stability and scalability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spin-transfer torque switching (STT-MRAM) is used to achieve non-volatile memory, then data retention and endurance are improved, but switching current density increases leading to high power consumption
Solution Approach 1:
The patent changes the material parameters by using ferrimagnetic materials (such as CoFeB, CoFe) with compensated magnetization instead of conventional ferromagnetic materials. This parameter change in magnetic moment compensation reduces the switching current density while maintaining non-volatile data retention, thereby lowering power consumption without sacrificing reliability
Solution Approach 2:
The patent employs composite material structures including ferrimagnetic layers combined with heavy metal layers (Ta, W) or topological insulator layers (Bi2Se3). These composite structures leverage spin-orbit coupling effects at the interfaces to achieve efficient magnetization switching at lower current densities, resolving the contradiction between data retention and power consumption
2Ease of operation
If conventional ferromagnetic materials are used in MRAM, then magnetization switching is achieved, but thermal stability is limited restricting high-temperature applications
Solution Approach 1:
The patent changes the magnetic material parameters by using ferrimagnetic materials with high Néel temperatures (such as CoFeB, CoFe) that maintain stable magnetization at elevated temperatures. The compensated magnetization structure provides enhanced thermal stability while preserving the ability to switch magnetization states, enabling both ease of operation and high-temperature stability
Solution Approach 2:
The patent replaces conventional thermal switching mechanisms with spin-current driven switching mechanisms utilizing spin-orbit coupling. This substitution allows magnetization switching without relying on thermal effects, thereby achieving thermal stability while maintaining ease of operation through current-controlled switching
3Ease of operation
If existing magnetic electrode structures are used, then magnetization control is achieved, but sensitivity to external magnetic fields limits scalability
Solution Approach 1:
The patent changes the magnetic moment compensation parameter in ferrimagnetic materials to create a magnetization structure that is inherently less sensitive to external magnetic fields. By balancing the magnetic moments of different sublattices, the net magnetization becomes more stable against external field perturbations while maintaining controllable switching, thus improving scalability
Solution Approach 2:
The patent creates an equipotential magnetic state through compensated magnetization where the opposing magnetic moments balance each other. This balanced state provides resistance to external magnetic field disturbances, allowing magnetization control to be maintained without being affected by external fields, thereby enabling scalable integration
4Ease of manufacture
If conventional material interfaces are used in magnetic devices, then device fabrication is achieved, but lattice disorder at interfaces reduces spin polarization and magnetoresistance
Solution Approach 1:
The patent changes the interface material parameters by using isoelectronic substitutions (such as Ta for W, or specific alloy compositions) that maintain similar atomic sizes and electronic structures. This parameter matching reduces lattice mismatch and interface disorder, preserving high spin polarization and magnetoresistance while keeping the device fabrication process feasible
Solution Approach 2:
The patent employs homogeneous material compositions and matched lattice parameters at the interfaces between different layers. By ensuring compositional and structural homogeneity at the interfaces, the patent minimizes lattice disorder and maintains high spin polarization, achieving both ease of manufacture through standard processes and high manufacturing precision in spin properties
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 magnetoresistance, thermal stability, and scalability, addressing the limitations of current MRAM technologies by maintaining high spin polarization and reducing power consumption.
Implementation Method 1
the relative (net) magnetisation orientation of the first and second magnetic electrode layers is switchable between a parallel and antiparallel (net magnetisation) state to control a spin-polarised current through the device
Implementation Method 2
maintaining a high spin polarisation across the interfaces with the spacer layer to provide high magnetoresistance (giant magnetoresistance, GMR, in the case of a spin valve configuration and tunnelling magnetoresistance, TMR, in the case of a MTJ configuration)
Implementation Method 3
All three layers share the same antiperovskite/perovskite lattice structure... The all-nitride nature of the tri-layer provides a less abrupt change in the lattice constituents at the interfaces between electrode layers and the spacer layer. The resulting low lattice disorder at the electrode-spacer interfaces ensures low scattering and high spin coherence
Implementation Method 4
The magnetic electrodes provide highly spin polarised conduction channels, but the challenge is maintaining a high spin polarisation across the interfaces with the spacer layer
Implementation Method 5
The all-perovskite structure provides high mechanical stability and good lattice match between the individual layers which promotes high quality interfaces and endurance. The resulting low lattice disorder at the electrode-spacer interfaces ensures low scattering and high spin coherence which contributes to maintaining a high spin polarization of the current across the interfaces
Data Source
Figure 1~4
Figure 2~3
Figure 5(a)~5(b)
AI summary
Disclosed is a magnetic device (100) comprising: a spacer layer (110); a first magnetic electrode layer (121) located on one side of the spacer layer; and a second magnetic electrode layer (122) located on the other side of the spacer layer; the spacer layer comprises a perovskite nitride material or perovskite oxynitride material; the first magnetic electrode layer and the second magnetic electrode layer respectively comprises a metallic antiperovskite nitride material; the relative net magnetization orientation of the first magnetic electrode layer and the second magnetic electrode layer is switchable between a parallel net magnetization state or an antiparallel net magnetization state to control a spin-polarised current therethrough. Also disclosed is a memory cell comprising the magnetic device, wherein the data is recordable as a parallel or antiparallel net magnetization state of the first magnetic electrode layer and the second magnetic electrode layer of the magnetic device.