Nitrogen Vacancy Sensor for Nanoscale Magnetic Head Characterization
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Solution Overview
Problem
Current metrology methods lack the necessary spatial resolution and quantitative information to characterize critical nanoscale features of magnetic recording heads, such as write poles and optical nano-apertures, in magnetic data storage systems.
Innovation Solution
A crystal film with nitrogen vacancy centers is placed in close proximity to a recording head, and a magnetic field or heat is applied, with excitation illumination and an excitation field used to measure Optically Detected Spin Resonance (ODMR) using a confocal or wide-field microscope, allowing for the determination of recording head characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical and magneto-optical metrology methods are used, then measurement can be performed, but spatial resolution is insufficient for nanometer-scale characterization
Solution Approach 1:
The patent introduces nitrogen vacancy (NV) centers in diamond as intermediary sensors that couple to the magnetic field of interest. These NV centers act as mediators between the write head's magnetic field and the optical detection system, enabling nanometer-scale spatial resolution through their optically detectable magnetic resonance signals while maintaining compatibility with standard optical metrology equipment.
Solution Approach 2:
The patent replaces conventional mechanical or direct optical measurement approaches with a quantum-based optical detection method. By using optically detected magnetic resonance (ODMR) of NV centers, the system substitutes traditional metrology mechanisms with a quantum sensing approach that achieves higher spatial resolution through optical means rather than mechanical contact or direct field measurement.
2Measurement precision
If Magnetic Force Microscopy is used, then high spatial resolution is achieved, but quantitative information about magnetic field strength is not provided
Solution Approach 1:
The NV centers in diamond serve multiple functions simultaneously: they provide high spatial resolution imaging through their localized magnetic field sensing capability, and they provide quantitative magnetic field strength information through the frequency shift of their ODMR signal. This single sensing mechanism delivers both qualitative (spatial distribution) and quantitative (field strength) data, eliminating the trade-off present in magnetic force microscopy.
Solution Approach 2:
The patent exploits the dependence of the NV center's magnetic resonance frequency on the applied magnetic field strength. By measuring the frequency shift of the ODMR signal, the system extracts quantitative information about the magnetic field strength at each spatial location, while the spatial distribution is obtained through scanning or imaging techniques. This parameter change (frequency with field strength) enables simultaneous acquisition of both spatial and quantitative magnetic field data.
3Manufacturing precision
If conventional metrology systems are used, then measurement can be performed, but nanoscale features such as optical nano-apertures cannot be adequately characterized
Solution Approach 1:
The NV centers serve as adaptable intermediary sensors that can characterize diverse nanoscale features including optical nano-apertures, write poles, and other magnetic recording head components. Their optical detection mechanism allows them to sense magnetic fields, thermal fields, and near-field optical effects at the nanometer scale, providing versatile characterization capability that conventional metrology systems lack.
Solution Approach 2:
The patent utilizes multiple physical parameters of the NV centers to characterize different features: magnetic field strength through ODMR frequency shifts, temperature through ODMR line shape changes, and near-field optical effects through photoluminescence intensity variations. This multi-parameter detection capability enables accurate characterization of various nanoscale features including optical nano-apertures used in heat-assisted magnetic recording, where conventional systems fail to provide adequate resolution or information.
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 method provides nanometer-scale spatial resolution and quantitative information about magnetic field strength and heat distribution, enabling accurate characterization of recording heads and improving metrology in magnetic data storage systems.
Implementation Method 1
measuring Optically Detected Spin Resonance (ODMR) by detecting a decrease in a spin dependent photoluminescence in response to the magnetic field, the excitation field and the excitation illumination caused by electron spin resonance (ESR) of the nitrogen vacancy centers
Implementation Method 2
measuring Optically Detected Spin Resonance (ODMR) by detecting a decrease in a spin dependent photoluminescence
Implementation Method 3
detecting a decrease in a spin dependent photoluminescence in response to the magnetic field, the excitation field and the excitation illumination
Implementation Method 4
the heat produced by a thermal device on the recording head
Data Source
AI summary
A crystal film with one or more nitrogen vacancy centers is placed in close proximity to a recording head. A magnetic field or heat produced by the recording head as well as excitation illumination and an excitation field is applied to the crystal film. The magnetic field produced by the recording head, the heat produced by a thermal device on the recording head, and/or the excitation field may be varied. A confocal microscope or wide-field microscope optically detects a decrease in a spin dependent photoluminescence in response to the magnetic field or heat, excitation field and excitation illumination caused by electron spin resonance (ESR) of the at least one nitrogen vacancy center to measure Optically Detected Spin Resonance (ODMR). A characteristic of the recording head is determined using the ODMR.