MAMR Head STO Current Timing for Magnetic Resonance
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Solution Overview
Problem
Magnetic hard disk drives face challenges in increasing recording density while maintaining thermal fluctuation resistance, as smaller particle volumes lead to magnetization reversal due to thermal fluctuations, and existing microwave-assisted magnetic recording (MAMR) techniques suffer from slow magnetization reversal and poor high-speed information transfer efficiency.
Innovation Solution
A MAMR head with a main pole and a spin torque oscillator (STO) that ramps up the STO drive current prior to the recording current to establish a magnetic resonance state, optimizing the recording conditions by adjusting the STO drive current and recording current to enhance recording density and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If recording density is increased by reducing particle volume, then more information can be stored in limited area, but thermal fluctuations cause magnetization reversal and decrease recording reliability
Solution Approach 1:
The patent applies spin torque oscillator to generate high-frequency magnetic fields that temporarily change the magnetic anisotropy energy barrier, enabling magnetization reversal at lower write fields. This allows use of smaller particles (higher recording density) while maintaining reliable writing capability through dynamic parameter modification rather than static field increase
Solution Approach 2:
The spin torque oscillator generates periodic high-frequency magnetic fields that cyclically modulate the magnetic properties of the recording medium. This periodic action creates temporary windows of opportunity for magnetization reversal, enabling reliable recording in small particles by synchronizing the write field application with the oscillation cycles
2Reliability
If magnetic anisotropy Ku is increased to suppress thermal fluctuations, then thermal stability improves, but the magnetic field required for magnetization reversal exceeds the recording head's capability
Solution Approach 1:
The spin torque oscillator dynamically modifies the magnetic anisotropy parameter during the writing process. By applying high-frequency fields, the effective anisotropy energy barrier is temporarily reduced, allowing the recording head to achieve magnetization reversal with its limited field capability while maintaining high Ku for thermal stability
Solution Approach 2:
The oscillator pre-modulates the magnetic state of the recording medium before the write field is applied. This preliminary action creates a transient state where the magnetic anisotropy is reduced, preparing the medium to be more responsive to the subsequent write field from the recording head
3Quantity of substance
If conventional MAMR technique is used to achieve high recording density, then recording density exceeds 1 Tbit/in2, but magnetization reversal is slow and information transfer efficiency is poor
Solution Approach 1:
The patent replaces conventional thermal-assisted or field-based switching mechanisms with spin torque oscillation. The spin-polarized current generates ultrafast magnetization precession and switching through spin transfer torque, eliminating the slow thermal diffusion processes and achieving sub-nanosecond switching speeds for high-speed information transfer
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
This approach enables high-density magnetic recording with improved thermal stability and faster information transfer by optimizing the STO drive current and recording current timing, reducing bit error rates and maintaining signal-to-noise ratio.
Implementation Method 1
a spin torque oscillator (STO) that ramps up the STO drive current prior to the recording current to establish a magnetic resonance state
Implementation Method 2
establish a magnetic resonance state
Implementation Method 3
a main pole configured to write data to a magnetic medium using a write magnetic field, a write coil, wherein the write magnetic field is produced by the main pole upon a recording current, Iw, being provided to the write coil
Data Source
AI summary
In one embodiment, a microwave-assisted magnetic recording (MAMR) head includes a main pole configured to write data to a magnetic medium using a write magnetic field, a write coil, wherein the write magnetic field is produced by the main pole upon a recording current, Iw, being provided to the write coil, and a spin torque oscillator (STO) positioned near the main pole, the STO being configured to provide a high-frequency assistance magnetic field to the magnetic medium upon a STO drive current, ISTO, being provided to the STO, wherein the STO drive current, ISTO, is ramped-up prior to the recording current, Iw, being provided to the write coil in order to begin a write operation for writing data to the magnetic medium. A method of operation for the MAMR head and an apparatus including the MAMR head are also described according to additional embodiments.