Achieving 5% 13C nuclear spin hyperpolarization in high-purity diamond at room temperature and low magnetic field
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2025-03-29 |
| Journal | Scientific Reports |
| Authors | Vladimir Vladimirovich Kavtanyuk, Changjae Lee, Keunhong Jeong, Jeong Hyun Shim |
| Institutions | Korea University of Science and Technology, Korea Research Institute of Standards and Science |
| Citations | 1 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: High-Purity Diamond for Nuclear Spin Hyperpolarization
Section titled âTechnical Documentation & Analysis: High-Purity Diamond for Nuclear Spin HyperpolarizationâExecutive Summary
Section titled âExecutive SummaryâThis research demonstrates a significant advancement in diamond-based quantum technology, achieving high levels of 13C nuclear spin hyperpolarization under practical conditions (Room Temperature and low magnetic field). The core value proposition relies entirely on the quality and purity of the Single Crystal Diamond (SCD) material.
- Record Polarization: Achieved 5% 13C nuclear spin hyperpolarization, equivalent to an enhancement ratio exceeding 7 x 106 over thermal polarization.
- Practical Conditions: Polarization achieved at Room Temperature (RT) and a low magnetic field of 9.4 mT, making the technique highly accessible for device integration.
- Material Purity Criticality: The high polarization and exceptional storage time (Tdepol > 100 min) were enabled by using ultra-high purity CVD-grown SCD with initial Nitrogen (N) concentration below 1 ppm.
- Orientation Optimization: Aligning the magnetic field along the [100] crystal orientation quadrupled the number of Nitrogen-Vacancy (NV) centers involved in the polarization transfer process.
- Mechanism: The polarization transfer is predominantly attributed to the Integrated Solid Effect (ISE) followed by nuclear spin diffusion, highly efficient in low-N concentration diamonds.
- Applications: This breakthrough is ideal for developing next-generation solid-state devices, including high-precision NMR gyroscopes, high-field magnetometers, and background-free MRI signal agents (RASER technology).
Technical Specifications
Section titled âTechnical SpecificationsâThe following table summarizes the critical performance metrics and material parameters extracted from the research.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Maximum 13C Polarization | 5 | % | Achieved at 9.4 mT |
| Polarization Enhancement Ratio | > 7 x 106 | N/A | Relative to thermal polarization |
| Optimal Low Magnetic Field (B) | 9.4 | mT | Used for hyperpolarization |
| NMR Readout Magnetic Field (B) | 6 | T | Used for signal quantification |
| Operating Temperature | Room Temperature | N/A | Enables practical device use |
| Initial N Concentration (Requirement) | < 1 | ppm | Critical for long Tdepol |
| Substitutional N (Ns) Concentration (Sample) | â 0.2 | ppm | Estimated concentration |
| NV Center Concentration (Sample) | â 0.3 | ppm | Estimated concentration |
| Polarization Build-up Time (Tpol) | 10.4 | min | Time to reach saturation at 9.4 mT |
| Depolarization Storage Time (Tdepol) | 102 | min | Measured at 6 T (Laser off) |
| Diamond Crystal Orientation | [100] | N/A | Optimized for NV alignment |
| Laser Wavelength | 532 | nm | Continuous optical pumping |
| Optimal MW Sweep Width | 6 | MHz | Minimal sweep width covering ODMR spectrum |
| Optimal MW Sweep Rate (ÎÌ) | 1.5 | MHz/ms | Achieved maximum polarization |
Key Methodologies
Section titled âKey MethodologiesâThe high 13C polarization was achieved through systematic optimization of material selection and experimental parameters, focusing on the Integrated Solid Effect (ISE) mechanism.
- Material Selection: Utilized a CVD-grown Single Crystal Diamond (SCD) with ultra-low nitrogen concentration (N < 1 ppm) and a [100] surface orientation.
- Low-Field Polarization Setup: The diamond sample was placed in a low magnetic field regime (optimized to 9.4 mT).
- Optical Pumping: Continuous laser irradiation (532 nm) was applied to optically polarize the NV electron spins.
- Microwave (MW) Irradiation: A repetitive, frequency-swept MW chirp was applied (e.g., 2.740-2.746 GHz sweep width) to transfer polarization from NV centers to 13C nuclei.
- Parameter Optimization: A comprehensive search was performed to determine the optimal relationships between:
- Magnetic Field (B) and MW Power (PMW).
- MW Sweep Width (Î) and Sweep Rate (ÎÌ).
- Rapid Shuttling: A swift shuttling mechanism transferred the hyperpolarized diamond sample (< 1.5 s) from the low-field polarization region to a high-field (6 T) superconducting magnet.
- NMR Readout: The 13C NMR signal was recorded at 6 T to quantify the achieved polarization level, normalized against a thermal polarization reference.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & Capabilitiesâ6CCVD is uniquely positioned to supply the high-specification diamond materials required to replicate, scale, and advance this hyperpolarization research for commercial applications in quantum sensing and medical imaging.
| Research Requirement | 6CCVD Solution & Capability | Technical Advantage & Sales Driver |
|---|---|---|
| Ultra-High Purity SCD (N < 1 ppm) | Optical Grade Single Crystal Diamond (SCD): Our MPCVD process ensures extremely low substitutional nitrogen (Ns) concentration, critical for minimizing decoherence. | Extended Tdepol and T2: Directly enables the long spin storage times (> 100 min) necessary for practical hyperpolarization storage and transfer, surpassing limitations of lower-grade materials. |
| Custom Crystal Orientation ([100]) | Precision Orientation Control: We offer SCD plates and wafers with custom crystallographic orientations, including [100], [110], and [111]. | Maximized NV Yield: Guarantees optimal alignment for the magnetic field, maximizing the number of NV centers contributing to the Integrated Solid Effect (ISE) polarization transfer. |
| Custom Dimensions & Mass (15 mg chip) | Custom Dimensions & Dicing: We supply SCD wafers (0.1 ”m to 500 ”m thickness) and offer precision laser cutting for custom chips and plates. | Experimental Flexibility: Provides researchers with samples perfectly tailored for specific MW cavities, NMR probes, or integration into microfluidic systems. |
| Integration for MW Delivery | In-House Metalization Services: We offer deposition of Au, Pt, Pd, Ti, W, and Cu films. | On-Chip Device Fabrication: Allows for the direct patterning of high-quality microwave transmission lines or antennas onto the diamond surface, enabling highly efficient PMW delivery and optimization of sweep parameters. |
| Scaling for RASER/Gyroscopes | Large-Area PCD/SCD Substrates: We provide PCD wafers up to 125 mm diameter and thick SCD substrates (up to 10 mm). | Commercial Viability: Supports the transition from small-scale lab experiments to scalable, high-volume manufacturing of diamond-based quantum sensors and NMR devices. |
Engineering Support
Section titled âEngineering Supportâ6CCVDâs in-house team of PhD material scientists and engineers provides expert consultation on material selection, defect engineering (e.g., controlled NV creation), and surface preparation (Ra < 1 nm polishing for SCD) for advanced hyperpolarization and quantum sensing projects.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Optically polarizable nitrogen-vacancy (NV) centers in diamond enable hyperpolarization of <sup>13</sup>C nuclear spins at a low magnetic field and room temperature. However, it remains a challenge to achieve a high level of polarization, comparable to that of conventional dynamic nuclear polarization. In this paper, we demonstrate that a <sup>13</sup>C polarization of 5%, equivalent to an enhancement ratio of over [Formula: see text], can be attained at less than 10 mT. We used a high-purity diamond with an initial nitrogen concentration below 1 ppm, which resulted in a storage time exceeding 100 min. Aligning the magnetic field along [100] increased the number of NV spins involved in polarization transfer by a factor of four. For this orientation, a comprehensive optimization of the magnetic field intensity and microwave (MW) sweep parameters has been performed. The optimum MW sweep width suggests that polarization transfer occurs primarily to the bulk <sup>13</sup>C spins through the integrated solid effect, followed by nuclear spin diffusion.
Tech Support
Section titled âTech SupportâOriginal Source
Section titled âOriginal SourceâReferences
Section titled âReferencesâ- 1970 - Spin Temperature and Nuclear Magnetic Resonance in Solids