Nitrogen-vacancy magnetometry of CrSBr by diamond membrane transfer
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2023-09-07 |
| Journal | npj 2D Materials and Applications |
| Authors | Talieh S. Ghiasi, Michael Borst, Samer Kurdi, Brecht G. Simon, Iacopo Bertelli |
| Institutions | Delft University of Technology, Parc CientĂfic de la Universitat de ValĂšncia |
| Citations | 12 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: MPCVD Diamond for 2D Magnetometry
Section titled âTechnical Documentation & Analysis: MPCVD Diamond for 2D MagnetometryâThis document analyzes the research paper âNitrogen-vacancy magnetometry of CrSBr by diamond membrane transferâ and maps the experimental requirements directly to the advanced manufacturing capabilities of 6CCVD.
Executive Summary
Section titled âExecutive SummaryâThis research successfully demonstrates a high-precision method for quantitative analysis of 2D magnetic materials using Nitrogen-Vacancy (NV) ensemble magnetometry, leveraging custom-fabricated Single Crystal Diamond (SCD) membranes.
- Nanoscale Proximity Achieved: A novel âdry-transferâ technique was developed to deterministically place a thin SCD membrane in direct contact with the 2D antiferromagnet CrSBr, achieving an NV-sample distance ($Z_0$) of approximately $130 \text{ nm}$.
- Quantitative Magnetization Extraction: The method enabled the extraction of the saturated monolayer magnetization ($M_s$) of CrSBr, quantified at $0.46(2) \text{ T}$, without requiring large external magnetic fields or monolayer exfoliation.
- Custom Diamond Requirements: The experiment relied on electronic-grade SCD chips etched into $50 \times 50 \times 5 \text{ ”m}^3$ membranes with shallow NV implantation (70 nm depth, $10^{13}/\text{cm}^2$ density).
- Detection of 2D Magnetic Order: The NV Electron Spin Resonance (ESR) measurements spatially resolved stray fields generated only by odd numbers of CrSBr layers, confirming the interlayer antiferromagnetic stacking order.
- Phase Transition Analysis: Temperature-dependent ESR measurements successfully tracked the decay of the stray field, accurately determining the NĂ©el temperature ($T_c$) of the CrSBr flake to be $130(1) \text{ K}$.
- 6CCVD Value Proposition: 6CCVD specializes in providing the high-purity, custom-dimension SCD membranes and precise ion implantation services necessary to replicate and advance this cutting-edge quantum sensing research.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the experimental setup and results:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Diamond Material Grade | Electronic-Grade SCD | N/A | Starting material for membrane fabrication |
| Membrane Dimensions | $50 \times 50 \times 5$ | ”m³ | Final etched size of the diamond sensor |
| NV Implantation Depth | $70 \pm 10$ | nm | Target depth for near-surface NV centers |
| Ion Implantation Energy | 54 | keV | Nitrogen ions used for NV creation |
| NV Density (Estimated) | $10^{13}$ (or $10^3$) | NVs / cm2 (or NVs / ”m2) | Resulting density after 800 °C anneal |
| Annealing Temperature (Max) | 800 | °C | Used for NV creation |
| External Bias Field ($B_{\text{ex}}$) | 5.6 | mT | Used for selective ESR driving |
| Monolayer Magnetization ($M_s$) | 0.46(2) | T | Extracted from stray field fit |
| NV-Sample Distance ($Z_0$) | 0.13(4) (or 130) | ”m (or nm) | Proximity achieved via dry-transfer |
| Critical Temperature ($T_c$) | 130(1) | K | NĂ©el temperature of CrSBr |
| Au Stripline Thickness | 100 | nm | Used for microwave delivery |
| NV Gyromagnetic Ratio ($\gamma_{\text{NV}}$) | 28.053 | GHz/T | Used for calculating ESR frequency shift |
Key Methodologies
Section titled âKey MethodologiesâThe experiment relied on precise MPCVD diamond processing, ion implantation, and advanced 2D material transfer techniques:
- SCD Preparation and Implantation: Electronic-grade SCD chips were cut and polished. Nitrogen ions were implanted at $54 \text{ keV}$ to achieve a target NV depth of $\approx 70 \text{ nm}$. The chips were then vacuum annealed up to $800 \text{ °C}$ to activate the NV centers.
- Membrane Etching: A Ti mask was defined using e-beam lithography. Reactive Ion Etching (RIE) using $\text{O}_2$ plasma was performed to etch the diamond into $50 \times 50 \times 5 \text{ ”m}^3$ squares, connected by small holding bars.
- Au Stripline Fabrication: A $5 \text{ nm}$ Ti adhesion layer and $100 \text{ nm}$ Au layer were deposited via e-beam evaporation and liftoff onto the $\text{SiO}_2/\text{Si}$ substrate adjacent to the exfoliated CrSBr flake.
- Dry Transfer (Detachment): A metallic tip was used to break the holding bars and detach a single diamond membrane onto a flexible Polydimethylsiloxane (PDMS) layer (PDMS 1).
- Dry Transfer (Pickup): A Poly-methyl methacrylate (PMMA)-PDMS stamp was used to pick up the diamond membrane from PDMS 1.
- Deterministic Placement: The diamond membrane was aligned and transferred onto the target CrSBr flake. The stage was heated to $180 \text{ °C}$ to melt the PMMA, allowing the flexible diamond membrane to conform and achieve direct contact with the CrSBr surface.
- NV ESR Measurement: A $520 \text{ nm}$ laser excited the NV centers. Microwaves were applied via the Au stripline, and the resulting spin-dependent photoluminescence (PL) was measured to detect the local magnetic stray field ($\text{dB}_{\text{NV}}$).
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & Capabilitiesâ6CCVD is uniquely positioned to supply the high-specification diamond materials and fabrication services required for quantum magnetometry research, enabling researchers to focus solely on experimental results.
Applicable Materials
Section titled âApplicable MaterialsâTo replicate or extend this research, 6CCVD recommends the following materials:
- Optical Grade Single Crystal Diamond (SCD): Required for high-fidelity quantum sensing applications. Our SCD material offers extremely low strain and defect density, maximizing the NV spin coherence time ($T_2$) essential for high magnetic sensitivity.
- Custom Ion Implantation Services: We provide precise control over the NV layer. For this application, we can deliver SCD wafers with Nitrogen implantation targeting $70 \text{ nm}$ depth and $10^{13}/\text{cm}^2$ density, ready for the customerâs final annealing step.
Customization Potential
Section titled âCustomization PotentialâThe success of this experiment hinges on the precise dimensions and integration of the diamond sensor. 6CCVD offers comprehensive customization capabilities:
| Research Requirement | 6CCVD Capability | Benefit to Researcher |
|---|---|---|
| Thin Membrane Fabrication | SCD Thickness Control (0.1 ”m - 500 ”m) | We can supply SCD membranes polished to the required $5 \text{ ”m}$ thickness, or even thinner (down to $0.1 \text{ ”m}$), to further reduce the NV-sample distance and minimize optical aberrations. |
| Micron-Scale Etching & Dicing | Custom Laser Cutting and RIE Etching | We can pre-fabricate the $50 \times 50 \text{ ”m}^2$ square features directly into the SCD substrate, eliminating the need for complex in-house RIE processing by the end-user. We handle plates/wafers up to $125 \text{ mm}$ (PCD). |
| Integrated Microwave Delivery | Internal Metalization Services | We offer deposition of the required stripline materials (Ti/Au, Pt, Pd, etc.) directly onto the diamond substrate or membrane, delivering a fully integrated sensor ready for microwave excitation. |
| Surface Quality | Polishing (Ra < 1 nm for SCD) | Our ultra-smooth polishing ensures the lowest possible surface roughness, which is critical for achieving the tightest possible NV-sample proximity during the dry-transfer process. |
Engineering Support
Section titled âEngineering Supportâ6CCVDâs in-house team of PhD material scientists and engineers provides expert consultation to optimize material selection and fabrication recipes. We can assist researchers in designing custom diamond substrates for similar 2D Magnetometry and Quantum Sensing projects, ensuring the optimal balance between NV depth, density, and material purity for maximum magnetic sensitivity.
Call to Action: For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly. We ship globally (DDU default, DDP available).
View Original Abstract
Abstract Magnetic imaging using nitrogen-vacancy (NV) spins in diamonds is a powerful technique for acquiring quantitative information about sub-micron scale magnetic order. A major challenge for its application in the research on two-dimensional (2D) magnets is the positioning of the NV centers at a well-defined, nanoscale distance to the target material required for detecting the small magnetic fields generated by magnetic monolayers. Here, we develop a diamond âdry-transferâ technique akin to the state-of-the-art 2D-materials assembly methods and use it to place a diamond micro-membrane in direct contact with the 2D interlayer antiferromagnet CrSBr. We harness the resulting NV-sample proximity to spatially resolve the magnetic stray fields generated by the CrSBr, present only where the CrSBr thickness changes by an odd number of layers. From the magnetic stray field of a single uncompensated ferromagnetic layer in the CrSBr, we extract a monolayer magnetization of M CSB = 0.46(2) T, without the need for exfoliation of monolayer crystals or applying large external magnetic fields. The ability to deterministically place NV-ensemble sensors into contact with target materials and detect ferromagnetic monolayer magnetizations paves the way for quantitative analysis of a wide range of 2D magnets assembled on arbitrary target substrates.