Hard Magnet Seed and Cap Layers for Low-Temperature FePt Ordering
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Solution Overview
Problem
Magnetic data storage devices face challenges in achieving high coercivity and saturation magnetization with smaller magnetic grain sizes, leading to decreased signal-to-noise ratio and increased thermal noise due to the limitations of current annealing processes for forming ordered phase constitution alloys like FePt.
Innovation Solution
A multilayer structure comprising a seed layer, a cap layer, and an intermediate alloy layer with specific components like Pt, Fe, Mn, or Ir, which facilitates the formation of high-anisotropy L10 phase alloys at lower annealing temperatures, enhancing coercivity and magnetic moment without degrading other components of the read head.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional annealing processes are used to form ordered phase constitution alloys like FePt, then the alloy achieves high coercivity and saturation magnetization, but the annealing temperature is too high which degrades other components of the read head
Solution Approach 1:
A seed layer comprising Pt-group metal, Fe, Mn, Ir or Co is introduced as an intermediary between the alloy layer and the read head components. This seed layer facilitates the formation of ordered phase constitution at lower annealing temperatures by providing a template for atomic ordering, thereby achieving high coercivity without exposing sensitive read head components to excessive temperatures
Solution Approach 2:
The invention employs a composite multilayer structure consisting of a seed layer, an alloy layer containing FePt or similar magnetic alloy, and a cap layer. This composite structure enables the alloy layer to develop high coercivity through controlled annealing at reduced temperatures while the seed and cap layers protect and support the overall structure during the annealing process
2Quantity of substance
If the magnetic grain size is reduced to increase storage density, then more data can be stored, but the signal-to-noise ratio decreases and thermal noise increases
Solution Approach 1:
The invention changes the magnetic properties parameters by forming an ordered phase constitution (L10 structure) in the alloy layer through controlled annealing. This phase transformation increases the saturation magnetization and coercivity of the magnetic grains, thereby maintaining higher signal-to-noise ratio even when grain size is reduced for increased storage density
3Strength
If high annealing temperatures are used to form ordered phase alloys, then high coercivity is achieved, but other components of the read head are degraded
Solution Approach 1:
The seed layer acts as a thermal buffer and catalytic intermediary that enables ordered phase formation at lower temperatures. It mediates between the high-temperature requirement for ordering and the low-temperature constraint imposed by heat-sensitive read head components, achieving coercivity enhancement without component degradation
Solution Approach 2:
The seed layer is deposited beforehand to provide a prepared surface that promotes low-temperature ordering. This preliminary action of creating a favorable interface structure allows the subsequent annealing process to achieve ordered phase constitution at reduced temperatures, protecting the read head components from thermal damage
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 approach allows for the production of FePt alloys with significantly higher coercivity and magnetic moment, enabling more stable and efficient magnetic data storage with smaller grain sizes and improved signal-to-noise ratios, while maintaining the integrity of the read head components.
Implementation Method 1
which facilitates the formation of high-anisotropy L10 phase alloys at lower annealing temperatures
Implementation Method 2
formation of high-anisotropy L10 phase alloys
Implementation Method 3
Hard magnet with cap and seed layers
Data Source
AI summary
A method including forming a multilayer structure. The multilayer structure includes a seed layer comprising a first component selected from the group consisting of a Pt-group metal, Fe, Mn, Ir and Co. The multilayer structure also includes an intermediate layer comprising the first component and a second component selected from the group consisting of a Pt-group metal, Fe, Mn, Ir and Co. The second component is different than the first component. The multilayer structure further includes a cap layer comprising the first component. The method further includes heating the multilayer structure to an annealing temperature to cause a phase transformation of the intermediate layer. Also a hard magnet including a seed layer comprising a first component selected from the group consisting of a Pt-group metal, Fe, Mn, Ir and Co. The hard magnet also includes a cap layer comprising the first component. The hard magnet further includes an intermediate layer between the seed layer and the cap layer. The intermediate layer includes the first component and a second component selected from the group consisting of a Pt-group metal, Fe, Mn, Ir and Co. The first component is different than the second component. Additionally, a read/write head including the hard magnet.