YIG-Heavy Metal Write Head Reducing Flux Shunting
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Solution Overview
Problem
Conventional magnetic recording heads face challenges in maintaining precise magnetic field gradients due to magnetic flux shunting from the main pole to the trailing shield, which affects the areal density and write-ability of magnetic media devices.
Innovation Solution
Incorporating a heavy metal layer between the main pole and the trailing shield, along with a yttrium-iron garnet (YIG) layer that acts as an electrical insulator and good spin current conductor, reduces shunting and enhances spin-orbit torque, thereby improving write-ability by fully utilizing charge current for spin current conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the gap between main pole and trailing shield is made small (20-30 nm) to increase magnetic field gradients, then write precision is improved, but magnetic flux shunting from main pole to trailing shield increases
Solution Approach 1:
A non-magnetic material layer is introduced as an intermediary between the main pole and trailing shield in the write gap. This intermediary layer blocks magnetic flux shunting paths while allowing the gap to remain small for high field gradients, thus resolving the contradiction between write precision and flux shunting
Solution Approach 2:
The write gap is filled with a composite structure combining non-magnetic materials that provide both electrical insulation and magnetic flux blocking. This composite approach prevents flux shunting while maintaining the narrow gap dimension needed for precision writing
2Reliability
If non-magnetic electrical insulating material (e.g., alumina) is used to fill the gap, then electrical insulation is improved, but magnetic flux shunting still occurs
Solution Approach 1:
The patent uses a specialized non-magnetic intermediary layer that provides dual functionality: electrical insulation to prevent charge current shunting and magnetic flux blocking to prevent magnetic flux shunting. This intermediary structure resolves the limitation of conventional alumina insulation
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 solution effectively reduces magnetic flux shunting, allowing for a narrower write gap and increased write field gradient, leading to improved write-ability and data storage capabilities.
Implementation Method 1
Spin-orbit torque (SOT) is generated from the heavy metal layer and transferred to a surface of the main pole as a current passes through the heavy metal layer in a cross-track direction
Implementation Method 2
The YIG layer is an electrical insulator, but also a good spin current conductor. Thus the charge current can be fully utilized for spin current conversion
Data Source
AI summary
The present disclosure generally relates to data storage devices, and more specifically, to a magnetic media drive employing a magnetic recording head. The head includes a main pole at a media facing surface (MFS), a trailing shield at the MFS, a heavy metal layer disposed between the main pole and the trailing shield at the MFS, and a yttrium-iron garnet (YIG) layer. Spin-orbit torque (SOT) is generated from the heavy metal layer and transferred to a surface of the main pole as a current passes through the heavy metal layer in a cross-track direction. The YIG layer is an electrical insulator, but also a good spin current conductor. Thus the charge current can be fully utilized for spin current conversion. The YIG layer does not dissipate energy because there is no shunting. With the reduced shunting from the main pole to the trailing shield, write-ability is improved.