Spatially resolved detection of complex ferromagnetic dynamics using optically detected nitrogen-vacancy spins
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2016-06-06 |
| Journal | Applied Physics Letters |
| Authors | C. S. Wolfe, S.A. Manuilov, C. M. Purser, R. Teeling-Smith, C Dubs |
| Institutions | The Ohio State University, Innovent |
| Citations | 25 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Spatially Resolved Detection of Ferromagnetic Dynamics using Optically Detected NV Spins
Section titled âTechnical Documentation & Analysis: Spatially Resolved Detection of Ferromagnetic Dynamics using Optically Detected NV SpinsâExecutive Summary
Section titled âExecutive SummaryâThis research demonstrates a highly versatile, off-resonant continuous wave (CW) detection scheme utilizing Nitrogen-Vacancy (NV) centers in diamond for studying complex ferromagnetic dynamics. This approach offers significant advantages for engineers developing next-generation spintronic and magnonic devices.
- Novel Detection Modality: The study employs a straightforward CW detection method, where NV photoluminescence (PL) responds directly to magnetic resonance excitation of a proximal ferromagnet (Yttrium Iron Garnet, YIG), eliminating the need for complex pulsed Optically Detected Magnetic Resonance (ODMR) sequences.
- Broad Spectral Range: The technique successfully detects ferromagnetic dynamics (FMR and spinwaves) across a wide range of parameters, achieving measurements up to 6.55 GHz and 180 mT, significantly exceeding the typical operational limits of conventional ODMR magnetometry.
- Spatial Resolution: By focusing the laser spot, the method achieves spatially resolved spectroscopy (resolution < 2 ”m), allowing localized study of magnetic dynamics induced by non-uniform microwave fields.
- Complex Dynamics Mapping: The NV centers successfully detected propagating dipolar spinwaves (kd < 1), dipolar-exchange spinwaves (1 †kd < 25), and dynamics associated with the multi-domain state of the YIG film.
- Application Potential: The results highlight the potential for using NV centers in this âoff-resonantâ modality for nanoscale imaging of domain wall motion, domain dynamics, and novel magnetic textures (e.g., skyrmions).
- Material Requirement: The success relies on the close proximity and high quality of the NV-rich diamond material relative to the magnetic film, a critical area where 6CCVD provides advanced solutions.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the research paper, detailing the experimental setup and achieved performance metrics.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| YIG Film Thickness (d) | 5 | ”m | Epitaxially grown on (111) GGG substrate. |
| Nanodiamond Size Range | 50 - 200 | nm | Used as the NV detector material (dispersed powder). |
| MW Excitation Frequency Range | 1.8 to 6.55 | GHz | Range tested for FMR and spinwave detection. |
| Maximum Applied Magnetic Field (H0) | 180 | mT | Limit of the current setup; FMR detected at 165 mT (6.55 GHz). |
| Spatial Resolution (Laser Spot) | < 2 | ”m | Demonstrated localized sensitivity to magnetic dynamics. |
| YIG Saturation Magnetization (4ÏMs) | 1760 | G | Used in spinwave dispersion calculations. |
| YIG Gyromagnetic Ratio (Îł) | 2.8 | MHz/Oe | Used in spinwave dispersion calculations. |
| Dipolar Spinwave Wavevector Range | kd < 1 | Dimensionless | Detected modes (Longitudinal Spinwaves, LSW). |
| Dipolar-Exchange Spinwave Range | 1 †kd < 25 | Dimensionless | Detected modes via first-order Suhl instability. |
| Silver Microstrip Thickness | 300 | nm | Lithographically patterned antenna for MW application. |
Key Methodologies
Section titled âKey MethodologiesâThe experiment utilized a specialized sample structure and an off-resonant CW optical detection technique to probe local magnetic dynamics.
- Substrate and Film Growth: A 5 ”m thick Yttrium Iron Garnet (YIG, Y3Fe5O12) film was grown epitaxially on a (111) oriented Gadolinium Gallium Garnet (GGG) substrate via liquid phase epitaxy.
- Microwave Antenna Fabrication: A 400 ”m wide, 300 nm thick silver (Ag) microstrip was lithographically patterned on the YIG film. A 25 ”m X 200 ”m window was left open in the center of the wire for optical access.
- NV Detector Application: Nanodiamond powder (50-200 nm) containing ensemble NV centers was dispersed on top of the sample structure.
- Excitation: The shorted microstrip was driven by a continuous wave (CW) microwave generator to apply dynamic magnetic fields (H1). A static external magnetic field (H0) was swept from -25 mT up to 180 mT.
- Detection: A 520 nm laser was focused to a < 2 ”m spot to excite the NV centers. The resulting photoluminescence (PL) intensity was monitored using a photodiode and lock-in detection, measuring the change in PL intensity as a function of H0 and MW frequency.
- Spatial Mapping: Measurements were taken at three distinct positions relative to the microstrip (center, edge/window, and far from the strip) to demonstrate the spatial sensitivity of the NV detection method.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe research successfully validates the use of NV centers for advanced magnonics and spintronics sensing. However, the use of dispersed nanodiamond powder introduces limitations in terms of NV depth control, spatial uniformity, and integration scalability. 6CCVD provides engineered MPCVD diamond solutions that directly address these challenges, enabling superior performance and commercial viability for similar projects.
Applicable Materials for Replication and Extension
Section titled âApplicable Materials for Replication and ExtensionâTo replicate or extend this research with enhanced sensitivity, integration, and scalability, 6CCVD recommends the following materials:
| Material | Recommended Specification | Value Proposition for Magnonics/Spintronics |
|---|---|---|
| Single Crystal Diamond (SCD) | Optical Grade SCD (High Purity, Low Strain) | Ideal for creating highly coherent, shallow NV layers (via implantation or in situ growth). Offers superior T2 coherence times compared to nanodiamonds, crucial for high-sensitivity magnetometry. |
| Shallow NV Layers | SCD with thickness control down to 0.1 ”m | Essential for maximizing coupling efficiency between the NV centers and the proximal magnetic film (YIG), improving signal-to-noise ratio for nanoscale dynamics detection. |
| Polycrystalline Diamond (PCD) | High-Quality PCD Wafers | Provides large-area substrates (up to 125 mm) for scalable fabrication of NV sensing arrays, suitable for industrial or high-throughput research applications. |
| Boron-Doped Diamond (BDD) | Heavy Boron Doped PCD | While not the primary detector, BDD can be used as a highly conductive electrode layer for integrated electrical excitation or readout components adjacent to the NV sensing layer. |
Customization Potential
Section titled âCustomization PotentialâThe experimental setup required precise material dimensions and specialized metallic contacts. 6CCVDâs internal capabilities ensure that researchers can obtain fully customized components optimized for their specific microwave and magnetic requirements:
- Custom Dimensions and Thickness: 6CCVD provides SCD and PCD plates/wafers with custom dimensions, including inch-size PCD wafers up to 125 mm diameter. We offer precise thickness control for both SCD and PCD from 0.1 ”m to 500 ”m.
- Superior Polishing: Achieving intimate contact between the diamond sensor and the magnetic film (YIG) is critical. 6CCVD guarantees ultra-smooth surfaces: Ra < 1 nm for SCD and Ra < 5 nm for inch-size PCD.
- Integrated Metalization: The paper utilized a 300 nm thick Ag microstrip. 6CCVD offers in-house deposition of critical metals for microwave circuitry and contacts, including Au, Pt, Pd, Ti, W, and Cu, allowing for robust, integrated antenna designs directly on the diamond substrate.
Engineering Support
Section titled âEngineering SupportâThe detection of complex dynamics, such as dipolar-exchange spinwaves and multi-domain state resonances, requires deep expertise in material science and quantum sensing physics.
6CCVDâs in-house PhD team specializes in optimizing diamond material parameters (NV density, depth, and orientation) for advanced quantum magnetometry and spintronics applications. We offer consultation services to assist researchers in selecting the optimal diamond substrate and fabrication recipe to maximize sensitivity and coherence for similar ferromagnetic dynamics and spinwave detection projects.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
We demonstrate optical detection of a broad spectrum of ferromagnetic excitations using nitrogen-vacancy (NV) centers in an ensemble of nanodiamonds. Our recently developed approach exploits a straightforward CW detection scheme using readily available diamond detectors, making it easily implementable. The NV center is a local detector, giving the technique spatial resolution, which here is defined by our laser spot, but in principle can be extended far into the nanoscale. Among the excitations, we observe the propagating dipolar and dipolar-exchange spinwaves, as well as dynamics associated with the multi-domain state of the ferromagnet at low fields. These results offer an approach, distinct from commonly used optically detected magnetic resonance techniques, for spatially resolved spectroscopic study of magnetization dynamics at the nanoscale.