Magnetoresistive Element Impact Sensor Integration
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Solution Overview
Problem
Existing magnetic disk drives face challenges in detecting collisions between the magnetic head and the recording medium, particularly for TMR elements with low resistance-temperature coefficients, and existing solutions complicate the manufacturing process or affect the characteristics of the magnetoresistive element.
Innovation Solution
A magnetic detector with a magnetoresistive element and an impact sensor, where the impact sensor has a similar layer structure to the magnetoresistive element but with an impact detecting layer that exhibits a greater change in magnetization direction upon impact, allowing for collision detection without affecting the magnetoresistive element's characteristics, and can be formed simultaneously with the magnetoresistive element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the free layer has a magnetostriction constant having a large absolute value to detect impact through inverse magnetostrictive effect, then impact detection capability is improved, but the magnetic anisotropy of the free layer greatly varies depending on stress and temperature, deteriorating the characteristics of the magnetoresistive element
Solution Approach 1:
The invention divides the magnetic head into two functional parts: the magnetoresistive element for reading and the impact sensor for collision detection. The impact sensor contains an impact detecting layer with large magnetostriction constant that is separate from the free layer of the magnetoresistive element, allowing impact detection without compromising the stability of the magnetoresistive element's magnetic characteristics.
Solution Approach 2:
The impact sensor is constructed as a copy of the magnetoresistive element's layer structure, including the same spacer layer, pinned layer, and antiferromagnetic layer, but replaces the free layer with an impact detecting layer having large magnetostriction constant. This copying approach allows the impact sensor to respond to mechanical stress while the original magnetoresistive element maintains its stable reading characteristics.
2Measurement precision
If a separate sensor is provided in the magnetic head for detecting collision, then impact detection capability is improved, but the manufacturing process becomes more complicated
Solution Approach 1:
The impact sensor is integrated with the magnetoresistive element by using the same layer structure and manufacturing process. Both elements are formed simultaneously during the magnetoresistive element fabrication process, merging the production of two functional components into a single manufacturing flow, thereby avoiding the need for separate sensor fabrication and reducing overall manufacturing complexity.
Solution Approach 2:
The layered structure serves dual purposes: the magnetoresistive element performs data reading while the impact sensor performs collision detection. This multi-functionality is achieved by configuring the impact sensor with the same layer stack as the magnetoresistive element, allowing a single manufacturing process to produce both functional elements with different detection capabilities.
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
Enables effective collision detection without compromising the characteristics of the magnetoresistive element and simplifies the manufacturing process by integrating the impact sensor with the magnetoresistive element, providing a flexible placement option for the impact sensor.
Implementation Method 1
the impact detecting layer having a magnetization direction that changes by an inverse magnetostrictive effect in response to distortion created in the impact detecting layer by an impact received by the magnetic detector
Implementation Method 2
a magnetoresistive element having a plurality of element-constituent layers that are stacked and include a free layer, the free layer having a magnetization direction that changes in response to a magnetic field to be detected by the magnetic detector
Data Source
AI summary
A magnetic detector includes a magnetoresistive element and an impact sensor. The magnetoresistive element has a plurality of element-constituent layers that are stacked and include a free layer having a magnetization direction that changes in response to a magnetic field to be detected by the magnetic detector. The impact sensor has a plurality of sensor-constituent layers that are made of materials the same as those of the element-constituent layers and stacked in the same order as the element-constituent layers. The plurality of sensor-constituent layers include an impact detecting layer corresponding to the free layer and having a magnetization direction that changes by an inverse magnetostrictive effect in response to distortion created in the impact detecting layer by an impact received by the magnetic detector. The impact detecting layer exhibits a greater amount of change in magnetization direction when the magnetic detector receives an impact, compared with the free layer.