Single-spin scanning magnetic microscopy with radial basis function reconstruction algorithm
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2020-05-04 |
| Journal | Applied Physics Letters |
| Authors | Cheng-Jie Wang, Rui Li, Bei Ding, Pengfei Wang, Wenhong Wang |
| Institutions | Chinese Academy of Sciences, University of Science and Technology of China |
| Citations | 4 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: High-Dynamic-Range NV Magnetometry
Section titled âTechnical Documentation & Analysis: High-Dynamic-Range NV MagnetometryâThis document analyzes the research paper âSingle-spin scanning magnetic microscopy with radial basis function reconstruction algorithmâ (arXiv:2002.12023v2) to highlight the critical role of high-quality MPCVD diamond and to propose specific material solutions available from 6ccvd.com.
Executive Summary
Section titled âExecutive SummaryâThe research successfully demonstrates an advanced NV center scanning magnetometry technique capable of efficiently imaging millitesla-range magnetic fields with high spatial acutance. The core value proposition relies entirely on the stability and quality of the diamond NV sensor.
- Application Focus: Efficient imaging of stray magnetic fields generated by exotic structures (e.g., skyrmions, domain walls) using Nitrogen-Vacancy (NV) centers in diamond.
- Dynamic Range Achievement: The scheme overcomes the linewidth limitation of standard ODMR by tracking the resonance frequency, enabling robust imaging of fields fluctuating up to 10 mT (simulated).
- High Acutance: Achieved a maximum detectable magnetic field gradient of 0.86 mT per pixel, significantly exceeding the limits of traditional ODMR methods.
- Reconstruction Algorithm: Utilizes the Radial Basis Function (RBF), specifically the Thin Plate Spline (TPS) algorithm, to accurately reconstruct the magnetic field from scattered resonance frequency contour lines.
- Sensitivity: The system demonstrated a sensitivity of 1.6 ”T/âHz using pulsed ODMR spectroscopy, requiring ultra-low strain, high-purity Single Crystal Diamond (SCD).
- 6CCVD Relevance: Replication and extension of this high-performance quantum sensing technique require the highest quality, low-strain, optical-grade MPCVD SCD substrates, a core offering of 6CCVD.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the analysis of the experimental results and simulations:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Maximum Detectable Gradient | 0.86 | mT per pixel | Key metric defining imaging acutance |
| Magnetic Field Fluctuation Range | Up to 10 | mT | Achieved in simulations (high dynamic range) |
| Sensitivity (Pulsed ODMR) | 1.6 | ”T/âHz | Measured sensitivity of the NV sensor |
| Bias Magnetic Field ($B_{z}$) | 5.5 | mT | Applied along the NV axis |
| MW Frequency Offset ($d$) | 12 | MHz | Assigned as the Full Width at Half Maximum (FWHM) |
| Spatial Resolution Context | 250 | nm | Scale bar used for reconstructed field images |
| Acquisition Time (4096 pixels) | ~5 | min | Efficient scanning speed for millitesla fields |
| RBF Smoothness Parameter ($\lambda$) | 1 x 10-9 | N/A | Used in the minimization of the energy function $E(f)$ |
Key Methodologies
Section titled âKey MethodologiesâThe experiment relies on precise control over the NV center environment and advanced signal processing:
- Sensor Preparation: The NV center was located in a pillar structure on the surface of a diamond bulk, ensuring proximity to the sample for nanoscale imaging.
- Scanning Setup: The sample (Fe3Sn2 thin film) was scanned over the fixed NV center using an Atomic Force Microscope (AFM) tuning fork, maintaining a height of hundreds of nanometers.
- MW Excitation: Microwaves were delivered via an external copper wire antenna, and the NV center was excited using a 532 nm laser (ODMR).
- Frequency Tracking: For each pixel, three excitation frequencies ($f_{-}, f_{0}, f_{+}$) were used. $f_{0}$ was the estimated resonance frequency, and $f_{\pm}$ were offset by a fixed value $d$ (FWHM).
- Dynamic Adjustment: The system dynamically adjusted $f_{0}$ for the next pixel based on the comparison of the normalized PL signals ($C_{0}$ vs. $C_{\pm}$), ensuring the excitation frequency remained within the spectrum linewidth despite large field fluctuations.
- Data Reconstruction: The map of resonance frequencies ($f_{0}$) was fed into the Radial Basis Function (RBF) algorithm, specifically utilizing the Thin Plate Spline (TPS) kernel, to reconstruct the continuous magnetic field map.
- Optimization: The reconstruction minimized a weighted energy function $E(f)$ that incorporated the measured PL contrast ($S_{i}$) and a smoothness constraint ($\lambda$), providing resilience against measurement noise.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThis research demonstrates the cutting edge of quantum sensing, requiring diamond materials with exceptional purity, low strain, and precise surface engineering. 6CCVD is uniquely positioned to supply the necessary MPCVD diamond components to replicate, scale, and advance this technology.
| Research Requirement | 6CCVD Solution & Capability | Technical Advantage for NV Magnetometry |
|---|---|---|
| High-Purity NV Host Material | Optical Grade Single Crystal Diamond (SCD), high-purity MPCVD growth. | Essential for achieving the reported 1.6 ”T/âHz sensitivity and long coherence times ($T_{2}$) required for pulsed ODMR protocols. |
| Nanoscale Surface Quality | SCD Polishing Service: Ra < 1 nm surface roughness. | Critical for minimizing surface noise, ensuring stable NV pillar fabrication, and maintaining precise scanning height (hundreds of nanometers) for 250 nm spatial resolution. |
| Custom Substrate Dimensions | SCD plates available up to 500 ”m thick; Substrates up to 10 mm thick. | Provides robust, low-strain bulk material necessary for creating the NV pillar structures and integrating into complex scanning setups. |
| Integrated MW Delivery | Custom Metalization Services: Ti, Pt, Au, Cu, W, Pd deposition. | Allows researchers to transition from external copper wire antennas to integrated on-chip coplanar waveguides (CPW) directly on the diamond surface, improving MW field homogeneity and efficiency. |
| Large-Area Scanning Platforms | Polycrystalline Diamond (PCD) plates up to 125 mm diameter, polished to Ra < 5 nm. | Ideal for scaling up the scanning stage, offering superior thermal management and mechanical stability compared to traditional materials. |
Engineering Support
Section titled âEngineering SupportâThe successful implementation of this high-dynamic-range tracking scheme requires precise material selection to optimize NV properties (e.g., NV density, strain, and surface termination). 6CCVDâs in-house PhD team specializes in tailoring MPCVD diamond growth parameters to meet the stringent requirements of quantum sensing applications, including high-acutance magnetic microscopy and similar quantum computing projects.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Exotic magnetic structures, such as magnetic skyrmions and domain walls, are becoming more important in nitrogen-vacancy center scanning magnetometry. However, a systematic imaging approach to mapping stray fields with fluctuations of several milliteslas generated by such structures is not yet available. Here, we present a scheme to image a millitesla magnetic field by tracking the magnetic resonance frequency, which can record multiple contour lines for a magnetic field. The radial basis function algorithm is employed to reconstruct the magnetic field from the contour lines. Simulations with shot noise quantitatively confirm the high quality of the reconstruction algorithm. The method was validated by imaging the stray field of a frustrated magnet. Our scheme had a maximum detectable magnetic field gradient of 0.86 mT per pixel, which enables the efficient imaging of millitesla magnetic fields.