Magnetic Coupling Layer Alloying for Perpendicular Magnetoresistive Elements
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Solution Overview
Problem
The use of Ir in the magnetic coupling layer of perpendicular magnetization type magnetoresistive effect elements weakens the fixing of magnetization directions, leading to decreased long-term stability and MR ratio due to lattice mismatch and negative uniaxial anisotropy energy.
Innovation Solution
Incorporating elements like Cr, Mn, Fe, and Co into the magnetic coupling layer alongside Ir to reduce lattice mismatch and increase uniaxial anisotropy energy, with specific layer configurations and thicknesses to enhance exchange coupling and maintain interface abruptness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If Ir is used in the magnetic coupling layer, then the exchange coupling strength is improved, but the lattice mismatch increases causing negative uniaxial anisotropy energy and weakened magnetization direction fixing
Solution Approach 1:
The patent applies composite materials by combining Ir with Ru and/or Rh in the magnetic coupling layer to form an alloy composition. This composite approach leverages the strong exchange coupling of Ir while mitigating its lattice mismatch issues through alloying with Ru and/or Rh, which have more compatible lattice parameters. The resulting composite material achieves both strong exchange coupling and positive uniaxial anisotropy energy for stable perpendicular magnetization direction fixing.
Solution Approach 2:
The patent changes the compositional parameters of the magnetic coupling layer by controlling the atomic ratios of Ir, Ru, and Rh within specific ranges (Ir: 50-90 at%, Ru: 5-30 at%, Rh: 0-20 at%). By adjusting these parameters, the patent optimizes the balance between exchange coupling strength and lattice mismatch, ensuring positive uniaxial anisotropy energy while maintaining strong antiferromagnetic coupling between the first and second fixed layers.
2Strength
If Ir is used in the magnetic coupling layer, then the exchange coupling is enhanced, but the MR ratio decreases due to negative uniaxial anisotropy energy
Solution Approach 1:
The patent uses composite materials (Ir-Rh and/or Ir-Ru alloys) in the magnetic coupling layer to simultaneously achieve strong exchange coupling and maintain positive uniaxial anisotropy energy. The alloy composition strengthens the antiferromagnetic coupling between fixed layers while preserving the tunnel magnetoresistive effect, thereby maintaining a high MR ratio essential for reliable memory operation.
Solution Approach 2:
The patent optimizes the compositional parameters of the magnetic coupling layer by controlling the atomic ratios of Ir, Ru, and Rh within specific ranges. This parameter optimization ensures that the exchange coupling strength is maximized while the uniaxial anisotropy energy remains positive, thereby maintaining a high MR ratio and reliable device performance.
3Force
If Ir is used in the magnetic coupling layer, then the exchange coupling field is increased, but the magnetization direction fixing is weakened due to lattice mismatch
Solution Approach 1:
The patent applies composite materials by alloying Ir with Ru and/or Rh in the magnetic coupling layer. This composite structure reduces the lattice mismatch inherent to pure Ir while maintaining strong exchange coupling. The alloy composition enables the magnetic coupling layer to provide strong exchange coupling field for fixing the magnetization directions of the first and second fixed layers in an antiparallel configuration along the perpendicular direction.
4Device complexity
If the magnetization direction of the magnetization fixed layer is not sufficiently fixed, then the device complexity is reduced, but the long-term stability decreases
Solution Approach 1:
The patent changes the compositional parameters of the magnetic coupling layer by controlling the atomic ratios of Ir, Ru, and Rh within specific ranges. This parameter optimization ensures that the uniaxial anisotropy energy is positive and the exchange coupling field is sufficient to fix the magnetization directions of the first and second fixed layers stably along the perpendicular direction, achieving long-term stability without increasing device complexity.
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 strengthens the fixing of magnetization directions along the perpendicular axis, improving long-term stability and MR ratio by increasing the positive uniaxial anisotropy energy and maintaining strong antiferromagnetic exchange coupling.
Implementation Method 1
The first fixed layer and the second fixed layer are magnetically coupled to each other by exchange coupling via the magnetic coupling layer such that magnetization directions of the first fixed layer and the second fixed layer are antiparallel to each other
Implementation Method 2
The first fixed layer and the second fixed layer are antiferromagnetically coupled to each other by an exchange coupling magnetic field via the magnetic coupling layer
Implementation Method 3
the TMR element that uses an insulation layer (tunnel barrier layer) as the non-magnetic spacer layer generally has high element resistance but can realize a high MR ratio
Implementation Method 4
A technology called 'spin injection magnetization reversal' in which a spin transfer torque (STT) is applied to the magnetization free layer from electron spins by causing a spin-polarized current to flow through the magnetization free layer
Implementation Method 5
the use of a perpendicular magnetization type TMR element that has perpendicular magnetic anisotropy... the magnetization direction of the reference layer is fixed along a perpendicular direction
Data Source
AI summary
A magnetoresistive effect element includes a magnetization fixed layer, a magnetization free layer, and a non-magnetic spacer layer that is stacked between the magnetization fixed layer and the magnetization free layer. The magnetization free layer includes a first free layer and a second free layer that are formed of a ferromagnetic material, and a magnetic coupling layer that is stacked between the first free layer and the second free layer. The first free layer and the second free layer are magnetically coupled to each other by exchange coupling via the magnetic coupling layer such that magnetization directions of the first free layer and the second free layer are antiparallel to each other. The magnetic coupling layer is a non-magnetic layer that includes Ir and at least one of the following elements: Fe, Co and Ni.