Quantitative Vectorial Magnetic Imaging of Multi-Domain Rock Forming Minerals Using Nitrogen-Vacancy Centers in Diamond

At a Glance

Metadata	Details
Publication Date	2017-08-23
Journal	SPIN
Authors	E. Farchi, Y. Ebert, D. Farfurnik, G Haim, R. Shaar
Institutions	Hebrew University of Jerusalem
Citations	19
Analysis	Full AI Review Included

Technical Documentation & Analysis: NV Magnetometry Substrates

Executive Summary

This research demonstrates the critical role of high-quality Single Crystal Diamond (SCD) substrates in achieving quantitative, high-resolution vectorial magnetic imaging using Nitrogen-Vacancy (NV) centers. 6CCVD specializes in providing the foundational diamond materials necessary to replicate and advance this cutting-edge paleomagnetometry research.

Core Achievement: Direct quantitative vectorial magnetic imaging of multi-domain rock minerals (magnetite dendrites) using a wide-field NV magnetic microscope.
Performance Metrics: Achieved 350 nm spatial resolution and high magnetic sensitivity (6 µT/√Hz per pixel), enabling the measurement of weak magnetic moments (down to 1.1 x 10^-11 Am²).
Material Requirement: The experiment relies on a high-purity, electronic-grade (100) SCD chip with an ultra-thin, high-density NV ensemble layer (10-15 nm deep).
Surface Criticality: Successful operation requires extremely low surface roughness (Ra < 0.02 µm cited, but lower is better) to minimize the stand-off distance (3-10 µm) and maximize spatial resolution.
6CCVD Advantage: 6CCVD supplies Optical Grade SCD wafers with superior polishing (Ra < 1 nm), ensuring minimal stand-off distance and optimal signal fidelity for next-generation NV sensing platforms.
Custom Integration: We offer custom dicing and metalization services (e.g., Ti/Au for MW antennas) to integrate the diamond sensor seamlessly into complex magnetic microscopy setups.

Technical Specifications

The following table summarizes the key material and performance parameters extracted from the research paper, focusing on the diamond substrate and sensor characteristics.

Parameter	Value	Unit	Context
Diamond Material Type	Electronic Grade SCD	N/A	Substrate for NV layer
Diamond Orientation	(100)	N/A	Crystallographic plane control
Diamond Chip Dimensions	4.5 x 4.5 x 0.3	mm	Custom size requirement
NV Layer Depth	10 - 15	nm	Critical for high spatial resolution
NV Ensemble Density	1.3 x 10¹¹	NV/cm²	Required concentration for wide-field imaging
Nitrogen Implantation Dose	2 x 10¹³	N/cm²	Used for NV creation
Magnetic Sensitivity	6	µT/√Hz	Per pixel performance
Spatial Resolution (Optical Limit)	350	nm	Inherent resolution of the setup
Required Sample Roughness (Ra)	0.02	µm	Necessary for close stand-off distance
Measurement Stand-off Distance	3 - 10	µm	Distance between diamond and sample

Key Methodologies

The successful implementation of NV magnetic microscopy relies on precise control over the diamond substrate properties and the subsequent measurement protocol.

Substrate Selection: Use of a high-purity, electronic-grade Single Crystal Diamond (SCD) chip with a (100) crystallographic orientation to host the NV centers.
NV Center Creation: Nitrogen implantation (2 x 10¹³ N/cm² dose at 10 keV) followed by annealing to create a high-density NV ensemble layer situated 10-15 nm beneath the polished surface.
Optical Pumping and Readout: Optical polarization of the NV spin state using a 532 nm green laser incident through the bottom-polished side of the diamond (EPI mode). Fluorescence (600-800 nm) is collected via a high-NA objective.
Spin Coherent Manipulation: Application of a frequency-swept microwave (MW) field, generated by an external MW antenna, to coherently drive the NV spin transitions.
ODMR Measurement: Continuous-Wave Optically Detected Magnetic Resonance (CW ODMR) measurements are performed by sweeping the MW frequency and recording the spin-state-dependent fluorescence intensity.
Vectorial Field Reconstruction: The ODMR spectra are fitted to a multi-Lorentzian function to extract the Zeeman splitting frequencies (Δ_0,+1 and Δ_0,-1). These values are used to calculate the magnetic field projection (B_||) along the four tetrahedral NV orientations, which are then transformed into a full quantitative magnetic field vector (B_x, B_y, B_z).
Sample Preparation: Rock samples are polished to a surface roughness of 0.02 µm and subjected to controlled magnetic treatments (e.g., Alternating Field demagnetization or Isothermal Remanent Magnetization).

6CCVD Solutions & Capabilities

6CCVD is uniquely positioned to supply the advanced diamond materials required for high-sensitivity NV magnetometry, ensuring optimal performance for paleomagnetic and quantum sensing applications.

Applicable Materials

To replicate or extend the high-resolution vectorial imaging demonstrated in this paper, researchers require the highest quality SCD substrates.

Optical Grade Single Crystal Diamond (SCD):
- Requirement Match: Provides the necessary low-strain, high-purity lattice structure essential for long NV coherence times (T₂) and high magnetic sensitivity.
- Orientation Control: Available in precise (100) orientation, matching the substrate used in the research for controlled NV alignment.
- Thickness: SCD wafers available from 0.1 µm up to 500 µm, allowing optimization of thermal management and optical path length.

Customization Potential

The research utilized a small, custom-sized diamond chip (4.5 x 4.5 x 0.3 mm) and required integration with an MW antenna. 6CCVD offers comprehensive post-processing services to meet these integration challenges.

Research Requirement	6CCVD Customization Capability	Technical Advantage
Custom Dimensions (4.5 x 4.5 mm chip)	Precision Laser Cutting & Dicing: We process plates/wafers up to 125 mm (PCD) and offer custom dicing for SCD chips to exact specifications.	Ensures perfect fit into existing microscope stages and holders.
Ultra-Smooth Surface (Ra < 0.02 µm needed)	Advanced Polishing: We guarantee Ra < 1 nm for SCD surfaces.	Superior Performance: Our polishing is 20x better than the paper’s requirement, minimizing the critical stand-off distance (3-10 µm) and maximizing spatial resolution.
MW Antenna Integration	Internal Metalization Services: We deposit thin films of Au, Pt, Pd, Ti, W, or Cu.	Enables direct fabrication of on-chip microwave antenna structures, improving MW field homogeneity and simplifying device assembly.
Substrate Thickness (0.3 mm)	Custom Thickness Control: SCD substrates available up to 500 µm, and thicker substrates (up to 10 mm) for specialized applications.	Allows engineers to optimize substrate rigidity and thermal properties for high-power laser operation.

Engineering Support

6CCVD’s in-house team of PhD material scientists and engineers provides expert consultation to optimize your NV sensing platform.

Material Selection: We assist researchers in selecting the optimal SCD grade (e.g., low-strain, high-purity) and crystallographic orientation to maximize NV center yield and magnetic coherence.
Integration Planning: Our team can advise on the best practices for surface preparation and metalization schemes to ensure robust integration of MW antennas and electrical contacts for similar NV-based Paleomagnetometry projects.
Global Logistics: We offer reliable global shipping (DDU default, DDP available) to ensure rapid delivery of critical components worldwide.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

Magnetization in rock samples is crucial for paleomagnetometry research, as it harbors valuable geological information on long term processes, such as tectonic movements and the formation of oceans and continents. Nevertheless, current techniques are limited in their ability to measure high spatial resolution and high-sensitivity quantitative vectorial magnetic signatures from individual minerals and micrometer scale samples. As a result, our understanding of bulk rock magnetization is limited, specifically for the case of multi-domain minerals. In this work, we use a newly developed nitrogen-vacancy magnetic microscope, capable of quantitative vectorial magnetic imaging with optical resolution. We demonstrate direct imaging of the vectorial magnetic field of a single, multi-domain dendritic magnetite, as well as the measurement and calculation of the weak magnetic moments of an individual grain on the micron scale. These results pave the way for future applications in paleomagnetometry and for the fundamental understanding of magnetization in multi-domain samples.

Tech Support

Original Source

DOI: https://doi.org/10.1142/s201032471740015x