Na in diamond - high spin defects revealed by the ADAQ high-throughput computational database
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2024-05-23 |
| Journal | npj Computational Materials |
| Authors | Joel Davidsson, William Stenlund, Abhijith S. Parackal, Rickard Armiento, Igor A. Abrikosov |
| Institutions | Linköping University |
| Citations | 8 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: High-Spin Sodium Defects in MPCVD Diamond
Section titled âTechnical Documentation & Analysis: High-Spin Sodium Defects in MPCVD DiamondâThis document analyzes the research paper âNa in diamond: high spin defects revealed by the ADAQ high-throughput computational databaseâ to provide technical specifications and align the findings with the advanced material capabilities of 6CCVD.
Executive Summary
Section titled âExecutive SummaryâThe research utilizes high-throughput computational screening (ADAQ/DFT) to identify novel, high-performance point defects in diamond, focusing on Sodium (Na) centers, which present significant advantages over the established Nitrogen-Vacancy (NV) center for quantum applications.
- Novel Defect Discovery: Computational screening of 21,607 defects identified Sodium (Na) substitutional (Nac) and vacancy (NaV) centers as highly promising quantum emitters.
- High Spin States: Nac defects exhibit stable high spin states (S=1 and S=3/2), while NaV defects are predicted to host a rare spin-2 ground state, enabling extended possibilities for spin control and sensing.
- Ideal Optical Window: Nac defects feature Zero Phonon Lines (ZPLs) in the near-infrared region (1.592 eV / 779 nm), ideal for biological quantum sensing applications (outside the visible range).
- Robust Photonic Properties: Nac defects show a high predicted Debye-Waller factor (up to 40% with Jahn-Teller effects included), indicating robust optical transitions and significantly lower spectral diffusion compared to the NV center (~3.2%).
- GHz ZFS: The negative charge state of Nac exhibits a Zero Field Splitting (ZFS) D value in the high GHz range (6739 MHz, HSE), crucial for efficient microwave spin manipulation.
- Material Requirement: Successful experimental realization of these defects requires ultra-high purity, low-strain Single Crystal Diamond (SCD) substrates suitable for precise ion implantation and subsequent high-temperature annealing.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the high-accuracy HSE DFT calculations for the most promising defects, Nac (Sodium substitutional) and NaV (Sodium vacancy).
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Total Defects Screened | 21,607 | Defects | ADAQ Database |
| Nac Neutral Ground State Spin (S) | 3/2 | - | Wide stability region |
| Nac Negative Ground State Spin (S) | 1 | - | Lowest energy state |
| Nac Neutral ZPL (HSE) | 1.592 | eV | Near-Infrared (779 nm) |
| Nac Negative ZPL (HSE) | 1.682 | eV | Near-Infrared |
| Nac Neutral TDM (HSE) | 6.8 | debye | Transition Dipole Moment |
| Nac Neutral Radiative Lifetime (Ï) | 13.5 | ns | Fast emission rate |
| Nac Debye-Waller Factor (HSE, JT included) | 40 | % | High robustness for optical applications |
| Nac Negative ZFS (D) | 6739 | MHz | Zero Field Splitting (HSE) |
| NaV Negative Ground State Spin (S) | 2 | - | Predicted rare high-spin state |
| NaV Negative ZPL (HSE, Allowed Transition) | 2.548 | eV | Visible range |
| Diamond Lattice Constant | 3.57 | Ă | Simulation parameter |
| PBE ZPL Underestimation | ~0.25 | eV | Mean difference vs. experiment |
Key Methodologies
Section titled âKey MethodologiesâThe computational discovery relied on a rigorous, multi-stage theoretical workflow combining high-throughput screening with high-accuracy verification.
- High-Throughput Screening: Initial screening of 21,607 defects was performed using the ADAQ (Automatic Defect Analysis and Qualification) framework, which utilizes automated workflows via the high-throughput toolkit (httk).
- DFT Calculations (Initial): Density Functional Theory (DFT) calculations were executed using the VASP package, employing the PBE (Perdew, Burke, and Ernzerhof) semi-local functional for rapid screening of formation energies, spin states, and ZPLs.
- Simulation Environment: Defects were simulated in a 4 x 4 x 4 cubic supercell containing 512 atoms at the gamma point.
- High-Accuracy Verification: Promising Na defects were studied further using the HSE06 hybrid functional (Heyd, Scuseria, and Ernzerhof) to achieve more accurate predictions of band gaps, ZPLs, and charge state stability.
- Vibronic Property Calculation: Phonon calculations for the neutral ground state were performed using Phonopy to determine the Jahn-Teller stabilization energy (EJT) and the Debye-Waller factor, critical for assessing spectral stability.
- Magneto-Optical Property Calculation: Zero Field Splitting (ZFS) tensors were calculated using the VASP implementation, and Transition Dipole Moments (TDM) were calculated to assess transition brightness and radiative lifetime (Ï).
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe computational results strongly motivate experimental verification and device integration of Na-related defects. 6CCVD provides the necessary high-quality MPCVD diamond materials and customization services required to replicate and extend this cutting-edge quantum research.
Applicable Materials
Section titled âApplicable MaterialsâTo successfully create and characterize high-spin Na defects via ion implantation, researchers require diamond substrates with extremely low background noise and high crystalline quality.
| Research Requirement | 6CCVD Solution | Technical Specification | Value Proposition |
|---|---|---|---|
| Ultra-High Purity Substrates | Electronic Grade Single Crystal Diamond (SCD) | Nitrogen concentration < 1 ppb; Boron concentration < 1 ppb. | Minimizes background NV centers and BDD-related spectral diffusion, ensuring isolated Na defect characterization. |
| Implantation Depth Control | Custom SCD Thickness | SCD wafers available from 0.1 ”m up to 500 ”m. | Allows precise matching of substrate thickness to the required Na ion implantation depth profile. |
| Device Integration | Polycrystalline Diamond (PCD) | Plates/wafers up to 125 mm in diameter. | Provides large-area platforms for high-throughput defect array fabrication and large-scale quantum sensing applications. |
| Surface Quality | Precision Polishing | SCD surface roughness (Ra) < 1 nm. | Essential for minimizing surface-related strain and spectral diffusion, critical for high Debye-Waller factor performance. |
Customization Potential
Section titled âCustomization PotentialâThe integration of quantum defects into functional devices often requires non-standard geometries and electrical contacts. 6CCVD offers comprehensive customization capabilities to meet these needs:
- Custom Dimensions: 6CCVD provides precise laser cutting and shaping services for both SCD and PCD materials, enabling the creation of micro-structures, waveguides, or custom-sized plates required for specific experimental setups.
- Metalization Services: The creation of stable charge states (e.g., Nac-1 or Nac0) often requires surface termination or electrical contacts. 6CCVD offers in-house metalization capabilities, including Ti, Pt, Au, Pd, W, and Cu, allowing researchers to define custom contact geometries directly on the diamond surface for charge state control and device biasing.
- Boron Doping (BDD): For experiments requiring controlled Fermi level shifting or electrochemical applications, 6CCVD supplies Boron-Doped Diamond (BDD) films, which can be used as conductive layers or electrodes adjacent to the high-spin Na defects.
Engineering Support
Section titled âEngineering SupportâThe paper highlights the complexity of predicting defect properties, noting significant differences between PBE and HSE functional results, particularly concerning the Jahn-Teller effect and the resulting Debye-Waller factor.
- Material Selection Consultation: 6CCVDâs in-house PhD team specializes in MPCVD growth and defect engineering. We offer expert consultation to assist researchers in selecting the optimal material purity, crystal orientation, and surface termination required for successful Na Ion Implantation and High-Spin Defect Stabilization.
- Process Optimization: We provide technical guidance on post-processing steps, such as annealing protocols, which are crucial for activating implanted Na ions and stabilizing the desired high-spin Nac or NaV configurations.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Abstract Color centers in diamond are at the forefront of the second quantum revolution. A handful of defects are in use, and finding ones with all the desired properties for quantum applications is arduous. By using high-throughput calculations, we screen 21,607 defects in diamond and collect the results in the ADAQ database. Upon exploring this database, we find not only the known defects but also several unexplored defects. Specifically, defects containing sodium stand out as particularly relevant because of their high spins and predicted improved optical properties compared to the NV center. Hence, we studied these in detail, employing high-accuracy theoretical calculations. The single sodium substitutional (Na C ) has various charge states with spin ranging from 0.5 to 1.5, ZPL in the near-infrared, and a high Debye-Waller factor, making it ideal for biological quantum applications. The sodium vacancy (NaV) has a ZPL in the visible region and a potential rare spin-2 ground state. Our results show sodium implantation yields many interesting spin defects that are valuable additions to the arsenal of point defects in diamond studied for quantum applications.