Spin-Orbit Thermal Sensor for Magnetic Head Fly-Height Control
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Solution Overview
Problem
Existing magnetic recording heads face challenges in thermal fly-height control and head protrusion due to temperature fluctuations, which can lead to destructive head/disk interactions, particularly in high-capacity storage devices like HDDs and tape drives.
Innovation Solution
A temperature detection device incorporating a ferromagnetic material and a spin-orbit torque (SOT) material is used to generate electric voltage signals in response to temperature gradients, utilizing the anomalous Nernst effect, spin Seebeck effect, and inverse spin Hall effect to monitor and regulate head temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If thermal fly-height control heating is applied to reduce spacing between head and disk, then fly-height control is improved, but head temperature increases causing thermal expansion and protrusion
Solution Approach 1:
The temperature detection device is segmented into distinct functional layers: ferromagnetic material for temperature sensing, SOT material for spin current generation, and separate heating elements for TFC. This segmentation allows independent optimization of each function and prevents thermal interference between components.
Solution Approach 2:
The ferromagnetic material serves as an intermediary between the temperature gradient and the detectable voltage signal. It converts thermal information into electrical signals through the anomalous Nernst effect, enabling non-contact temperature monitoring that doesn't interfere with the heating process.
2Productivity
If write current is applied to write coil for data writing, then recording function is improved, but head element heats up and expands causing protrusion
Solution Approach 1:
The temperature detection device is integrated into the head structure before writing operations begin. This allows continuous monitoring of write element temperature during recording operations, enabling real-time detection of thermal expansion effects.
Solution Approach 2:
The detection device provides feedback about head temperature and protrusion conditions. This feedback can be used to adjust write current parameters or activate compensatory mechanisms to prevent excessive thermal expansion and maintain accurate fly-height control during recording operations.
3Productivity
If assistive energy is injected for energy assisted magnetic recording, then recording capability is improved, but head expansion and protrusion increases
Solution Approach 1:
The invention addresses thermal effects by moving from a single-dimensional approach (monitoring only spacing) to multi-dimensional monitoring that includes temperature, thermal gradients, and their temporal evolution. This is achieved through the layered SOT structure that detects temperature information from different orientations.
Solution Approach 2:
The detection device monitors changes in temperature parameters during energy-assisted recording operations. By detecting temperature gradients and thermal expansion effects, the system can adjust recording parameters or activate compensation mechanisms to maintain performance while preventing excessive protrusion.
4Manufacturing precision
If temperature monitoring is implemented to control fly-height, then spacing control accuracy is improved, but device complexity increases
Solution Approach 1:
The temperature detection device is designed to perform multiple functions: temperature sensing, thermal gradient detection, and protrusion monitoring. The same layered structure serves as both the detection element and part of the thermal management system, reducing overall device complexity.
Solution Approach 2:
The ferromagnetic material in the detection device generates the voltage signal automatically in response to temperature gradients without requiring external power or complex processing. The structure itself serves as the sensing element, eliminating the need for separate sensors and reducing system 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
Enhances temperature monitoring and regulation, improving fly-height control and reducing head protrusion, thereby enhancing the reliability and performance of magnetic recording heads.
Implementation Method 1
The FM material is configured to produce a first electric voltage signal in response to a temperature gradient due to an anomalous Nernst effect
Implementation Method 2
The SOT material is configured to receive a spin current parallel to the temperature gradient generated by a spin Seebeck effect in the FM materials
Implementation Method 3
The spin current being detectable as a second electric voltage signal via an inverse spin Hall effect
Data Source
AI summary
The present disclosure generally relates to temperature detection devices including a ferromagnetic (FM) material disposed at a media facing surface (MFS). The FM material is configured to produce a first electric voltage signal in response to a temperature gradient due to an anomalous Nernst effect. The temperature detection device may also include a spin-orbit torque (SOT) material abutting the FM material. The SOT material includes at least one of BiSb, a topological insulator, a topological half-Heusler alloy, or a weakly oxidized heavy metal. The SOT material is recessed from the MFS, wherein the SOT material is configured to receive a spin current parallel to the temperature gradient generated by a spin Seebeck effect in the FM material. The spin current is detectable as a second electric voltage signal via an inverse spin Hall effect. The first electric voltage signal is added to the second electric voltage signal.