Magnetic Recording Head Spacer Layer Current Density Control
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Solution Overview
Problem
Existing magnetic recording heads using energy-assisted magnetic recording (EAMR) face performance degradation due to high bias current densities causing magnetization tilting and slowed switching of the spin torque layer, leading to reduced areal density capability and recording quality.
Innovation Solution
A magnetic recording head design featuring a spacer layer with a reduced cross-sectional area compared to the spin torque layer, enhancing current density at the interface and improving magnetization switching efficiency through exchange coupling, thereby reducing performance degradation and increasing areal density capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high amount of bias current is applied to enhance write-ability, then recording quality is improved, but magnetization tilting occurs at the hot seed layer or notch layer of the trailing shield due to strong local spin transfer torque, resulting in performance degradation
Solution Approach 1:
The spacer layer is designed with non-uniform thickness, being thinner at the trailing edge region compared to other regions. This local variation in thickness creates a non-uniform current density distribution, concentrating current flow away from the hot seed layer or notch layer of the trailing shield, thereby reducing local spin transfer torque and preventing magnetization tilting while maintaining overall recording quality
Solution Approach 2:
The invention changes the geometric parameter of the spacer layer (thickness and lateral dimensions) to control current density distribution. By adjusting the spacer layer dimensions, the current path is modified to reduce peak current density at critical regions, thereby mitigating the harmful effects of high bias current while preserving the necessary write field strength
2Measurement precision
If a high amount of bias current is applied to improve write-ability, then recording quality is enhanced, but switching speed of the magnetization in the spin torque layer is slowed down, leading to performance degradation
Solution Approach 1:
The non-uniform spacer layer thickness creates regions of different current density, optimizing the local conditions for spin torque layer switching. The thinner region at the trailing edge allows sufficient current to pass through the spin torque layer to maintain fast switching, while the overall current distribution is optimized to prevent excessive heating and magnetization tilting
3Measurement precision
If an increased bias current density is applied at the hot seed layer or notch layer to enhance write-ability, then recording quality is improved, but the switching of magnetization in the spin torque layer is further slowed down, resulting in performance degradation
Solution Approach 1:
The spacer layer is engineered with spatially varying thickness to create a non-uniform current density profile. The trailing edge region has reduced thickness to minimize current density at the hot seed layer or notch layer, preventing magnetization tilting and maintaining fast switching response time, while other regions provide sufficient current for high-quality recording
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 design enables faster and more complete magnetization switching, enhancing the areal density capability and reducing performance degradation at high bias currents, resulting in improved recording quality and efficiency.
Implementation Method 1
a spin torque layer (STL) that is magnetized by a bias current during operation
Implementation Method 2
the STL switches and provides a DC magnetic field to the recording medium
Implementation Method 3
enhancing current density at the interface and improving magnetization switching efficiency through exchange coupling
Data Source
AI summary
The present disclosure generally relates to a magnetic media drive employing a magnetic recording head. The magnetic recording head comprises a main pole, an EAMR stack disposed on the main pole, and a trailing shield disposed on the EAMR stack. The EAMR stack comprises a seed layer disposed on the main pole, a spin torque layer disposed on the seed layer, and a spacer layer disposed on the spin torque layer. At least one surface of the spacer layer in contact with the spin torque layer has a smaller or reduced area than the spin torque layer. The at least one surface of the spacer layer in contact with the spin torque layer is recessed from a media facing surface and has a smaller cross-track width than the spin torque layer and a smaller width in the stripe height direction than the spin torque layer.