Nanoscale Magnetic Domains in Polycrystalline Mn3Sn Films Imaged by a Scanning Single-Spin Magnetometer
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2023-05-23 |
| Journal | Nano Letters |
| Authors | Senlei Li, Mengqi Huang, Hanyi Lu, Nathan J. McLaughlin, Yuxuan Xiao |
| Institutions | University of California, San Diego, Colorado State University |
| Citations | 19 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Nanoscale Magnetic Domain Imaging via NV Magnetometry
Section titled âTechnical Documentation & Analysis: Nanoscale Magnetic Domain Imaging via NV MagnetometryâThis document analyzes the research detailing the use of scanning Nitrogen-Vacancy (NV) single-spin magnetometry to image nanoscale magnetic domains in polycrystalline Mn3Sn films. This work validates the critical role of high-quality Single Crystal Diamond (SCD) in advancing next-generation quantum sensing and spintronic applications.
Executive Summary
Section titled âExecutive Summaryâ- Core Achievement: Direct, nanoscale imaging of magnetic domains in polycrystalline Mn3Sn, a noncollinear antiferromagnet, using a scanning single-spin Nitrogen-Vacancy (NV) magnetometer.
- Resolution Breakthrough: Achieved spatial resolution in the tens of nanometers range, overcoming the optical diffraction limit that constrains traditional magnetometry techniques (e.g., MOKE).
- Driving Forces Investigated: Systematically studied the evolution of stray field patterns in response to large external magnetic fields (up to 2.5 T) and current-induced Spin-Orbit Torques (SOTs).
- Key Finding: Revealed heterogeneous, âpartialâ magnetic switching and nonreversible domain reconstruction in Mn3Sn/W heterostructures driven by electrical currents.
- Material Validation: Confirms the NV center in diamond as a powerful, non-invasive quantum metrology tool essential for exploring microscopic spin properties in emergent condensed matter systems like Mn3X compounds.
- 6CCVD Value Proposition: The success of this research hinges on high-purity, precision-polished Single Crystal Diamond (SCD) platforms, a core specialization of 6CCVD.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the experimental methodology and results:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Mn3Sn Film Thickness Range | 30 to 400 | nm | Sputter deposited polycrystalline films studied. |
| Mn3Sn Film Thickness (SOT Device) | 70 | nm | Optimized thickness for Mn3Sn/W Hall cross device. |
| W Capping Layer Thickness (SOT Device) | 7 | nm | Used to generate Spin-Orbit Torques (SOTs). |
| Measurement Temperature | 300 | K | Room temperature quantum sensing measurements. |
| External Training Field (Pre-magnetization) | ±2.5 | T | Perpendicular field applied to set magnetic state. |
| Bias Field (During Scanning NV) | ~15 | G | Static field applied to distinguish NV ESR splitting. |
| Spatial Resolution (Vertical Distance) | ~60 | nm | Vertical distance between NV sensor and sample surface. |
| Anomalous Hall Resistivity (ÏH) | ~2 | ”Ω cm | Extracted from the 70 nm Mn3Sn film. |
| Current Switching Efficiency | ~40 | % | Achieved for electrically driven switching in Mn3Sn films. |
| Write Current Range (Iwrite) | -40 to 40 | mA | Current pulses applied for SOT-driven switching. |
| Average Domain Size (30 nm film) | Tens of | nm | Fragmented domains observed in thinner films. |
| Average Domain Size (400 nm film) | ~700 | nm | Increased domain size observed in thicker films. |
Key Methodologies
Section titled âKey MethodologiesâThe experimental success relied on precise material synthesis and the application of advanced quantum sensing techniques:
- Film Synthesis: Polycrystalline Mn3Sn thin films (30 nm to 400 nm) were prepared using magnetron sputtering techniques on Al2O3 and Si substrates.
- Device Fabrication: Mn3Sn (70 nm)/W (7 nm) bilayers were patterned into standard Hall cross devices for magneto-transport characterization and current-induced switching studies.
- Material Characterization: X-ray diffraction (XRD) confirmed the polycrystalline nature of the films, suggesting co-existing magnetic grains with kagome planes parallel and perpendicular to the substrate surface.
- Quantum Sensing Platform: A scanning NV microscope was utilized, employing a diamond cantilever containing a single NV center attached to a quartz tuning fork for force-feedback Atomic Force Microscopy (AFM).
- Magnetic Detection: Local magnetic stray fields (Bz component) were diagnosed via the Zeeman effect, optically detected using NV electron spin resonance (ESR) measurements.
- Switching Protocol: Samples were subjected to large perpendicular magnetic training fields (±2.5 T) or electrical write current pulses (Iwrite) to induce and visualize magnetic reversal at the nanoscale.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThis research underscores the necessity of high-purity, engineered diamond materials for cutting-edge quantum sensing applications. 6CCVD is uniquely positioned to supply the foundational diamond platform and necessary integration services to replicate and extend this work.
| Research Requirement | 6CCVD Solution & Capability | Technical Advantage |
|---|---|---|
| NV Quantum Sensing Platform | Optical Grade Single Crystal Diamond (SCD) | We provide SCD plates up to 125mm with ultra-low nitrogen concentration, essential for maximizing the NV center coherence time (T2) and achieving the highest magnetic sensitivity required for noncollinear antiferromagnets. |
| Custom Cantilever Fabrication | Custom Dimensions & Precision Cutting | 6CCVD supplies SCD plates in precise thicknesses (0.1 ”m - 500 ”m) suitable for micro-machining into high-Q scanning NV cantilevers, ensuring optimal mechanical and optical performance. |
| Surface Quality for High Resolution | Ultra-Low Roughness Polishing (Ra < 1nm) | Achieving the critical ~60 nm vertical distance for nanoscale resolution demands atomically flat diamond surfaces. Our SCD polishing achieves Ra < 1nm, guaranteeing maximum spatial resolution for imaging stray fields. |
| Spintronic Heterostructure Integration | Custom Metalization Services (Ti, W, Pt, Au) | The Mn3Sn/W bilayer requires a high-quality W capping layer for efficient SOT generation. 6CCVD offers internal metalization capabilities, including W, Ti, Pt, and Au deposition, ensuring robust electrical contacts and high-quality interfaces. |
| Engineering Support | In-House PhD Material Consultation | 6CCVDâs expert team can assist researchers in optimizing material selection and post-processing parameters (e.g., implantation and annealing recipes) for NV creation in SCD, specifically tailored for similar Quantum Sensing and Topological Spintronics projects. |
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Noncollinear antiferromagnets with novel magnetic orders, vanishingly small net magnetization, and exotic spin related properties hold enormous promise for developing next-generation, transformative spintronic applications. A major ongoing research focus of this community is to explore, control, and harness unconventional magnetic phases of this emergent material system to deliver state-of-the-art functionalities for modern microelectronics. Here we report direct imaging of magnetic domains of polycrystalline Mn<sub>3</sub>Sn films, a prototypical noncollinear antiferromagnet, using nitrogen-vacancy-based single-spin scanning microscopy. Nanoscale evolution of local stray field patterns of Mn<sub>3</sub>Sn samples are systematically investigated in response to external driving forces, revealing the characteristic âheterogeneousâ magnetic switching behaviors in polycrystalline textured Mn<sub>3</sub>Sn films. Our results contribute to a comprehensive understanding of inhomogeneous magnetic orders of noncollinear antiferromagnets, highlighting the potential of nitrogen-vacancy centers to study microscopic spin properties of a broad range of emergent condensed matter systems.