Probing stress and magnetism at high pressures with two-dimensional quantum sensors
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2025-09-01 |
| Journal | Nature Communications |
| Authors | G. He, Ruotian Gong, Zhipan Wang, Zhongyuan Liu, Jeonghoon Hong |
| Institutions | Washington University in St. Louis, Harvard University |
| Citations | 6 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled “Executive Summary”This research introduces a novel, integrated quantum sensing platform utilizing Boron-Vacancy (VB-) centers in two-dimensional (2D) hexagonal Boron Nitride (hBN) flakes placed directly inside a Diamond Anvil Cell (DAC).
- Core Innovation: Seamless integration of 2D VB- quantum sensors directly into the high-pressure chamber, enabling in situ mapping of local stress and magnetic fields.
- Pressure Range: Successfully characterized VB- spin properties and performed sensing up to 3.5 GPa.
- Stress Sensitivity Advantage: VB- sensors exhibit a response to local stress approximately three times stronger than conventional Nitrogen-Vacancy (NV) centers embedded in diamond anvils.
- Stress Susceptibility: Measured pressure-induced spin energy shift (stress susceptibility) is (2π) × (43 ± 7) MHz/GPa.
- Heterogeneous Sensing Demonstrated: Successfully imaged a pressure-driven magnetic phase transition in a self-intercalated van der Waals ferromagnet (Cr1+δTe2), transitioning from ferromagnetic to non-magnetic behavior around 0.5 GPa.
- Proximity and Resolution: The 2D nature of the sensor provides nanoscale proximity to the target sample, crucial for imaging interfacial phenomena in heterogeneous devices.
Technical Specifications
Section titled “Technical Specifications”| Parameter | Value | Unit | Context |
|---|---|---|---|
| Maximum Pressure Achieved | 3.5 | GPa | Limit before ODMR contrast vanishes (using NaCl medium) |
| Stress Susceptibility (VB-) | (2π) × (43 ± 7) | MHz/GPa | Pressure-induced spin energy shift |
| Stress Sensitivity (np) | ~0.2 | GPa Hz-1 | Estimated sensitivity of VB- sensors |
| Magnetic Sensitivity (nB) | ~3.1 | GHz-1 | Estimated sensitivity at 0.6 GPa |
| Zero-Field Splitting (Dgs) | (2π) × 3.48 | GHz | VB- ground state at 0 GPa |
| Hyperfine Coupling (Azz) | (2π) × 65.5 | MHz | Interaction with three nearby 15N nuclei at 0 GPa |
| Azz Pressure Dependence | (2π) × (0.5 ± 0.2) | MHz/GPa | Increase in hyperfine coupling with pressure |
| Magnetic Transition Pressure | ~0.5 | GPa | Ferromagnetic to non-magnetic transition in Cr1+δTe2 |
| hBN Flake Thickness | 50 - 100 | nm | Thickness of the 2D quantum sensor layer |
| External Magnetic Field (Bext) | 84 | G | Applied along the loading axis (out-of-plane) |
| Diamond Anvil Culet Diameter | 400 | µm | Diameter of the opposing anvils |
| Gasket Hole Diameter | 133 | µm | Sample chamber size |
| Microwave Delivery Width | 50 | µm | Width of the Platinum (Pt) foil wire |
Key Methodologies
Section titled “Key Methodologies”The experimental setup relies on precise material synthesis and careful heterogeneous integration within a miniature DAC.
1. hBN Sensor Synthesis (Isotopically Purified 10B15N)
Section titled “1. hBN Sensor Synthesis (Isotopically Purified 10B15N)”- Precursors: Mixture of Chromium (48.1 wt%), Nickel (48.1 wt%), and Boron-10 enriched powder (3.8 wt%).
- Growth Method: High-temperature process in a horizontal alumina furnace.
- Temperature Profile: Ramped to 1550 °C (24 h dwell), followed by slow cooling (1 °C/h to 1500 °C, then 50 °C/h to 1350 °C).
- Atmosphere: Vacuumed (<80 microtorr), then filled with 90% 15N2 (enriched) and complimented with H2 (total pressure 850 torr).
- VB- Creation: Ensemble VB- defects created via neutron irradiation (fluence: 1.4 × 1016 neutrons/cm2).
2. Cr1+δTe2 Magnet Synthesis
Section titled “2. Cr1+δTe2 Magnet Synthesis”- Growth Method: Chemical Vapor Deposition (CVD) in a three-zone quartz tube furnace.
- Precursors: CrCl3 and Te powders, placed in separate alumina boats.
- Temperature Zones: Zone 1 (CrCl3) at 500 °C; Zone 2 and 3 (Te and substrates) at 750 °C.
- Carrier Gas: 1% H2 and 99% Ar mixture.
- Pressure: Maintained at 50 Torr during the heat-up process.
3. DAC Heterostructure Assembly
Section titled “3. DAC Heterostructure Assembly”- Stacking: The hBN flake (~100 nm) was transferred directly onto the diamond anvil culet. The Cr1+δTe2 nanoflake (~5 µm lateral dimension) was placed on top of the hBN sensing layer.
- Microwave Delivery: A 50 µm wide Platinum (Pt) foil wire was placed across the heterostructure to deliver the coherent microwave field for ODMR measurements.
- Pressure Medium: Sodium Chloride (NaCl) was loaded into the sample chamber (133 µm diameter) to provide a quasi-hydrostatic environment.
- Calibration: Ruby microspheres were loaded on the opposite side of the Pt foil for standard pressure calibration via R2 fluorescence shifts.
4. Sensing and Measurement
Section titled “4. Sensing and Measurement”- Technique: Optically Detected Magnetic Resonance (ODMR) spectroscopy.
- Function: Sweeping the microwave frequency while detecting the VB- fluorescence signal to measure ZFS shifts (stress) and Zeeman splitting (magnetic field).
- Stress Mapping: ZFS shifts were used to calculate the lateral stress profile (σxx + σyy)/2 across the sample chamber.
Commercial Applications
Section titled “Commercial Applications”This integrated 2D quantum sensing platform is highly relevant for advancing research and development in extreme environments and quantum technologies.
| Industry/Field | Application | Relevance to VB-/hBN Platform |
|---|---|---|
| High-Pressure Materials Science | Probing pressure-induced superconductivity and novel magnetic phases. | High sensitivity and ability to map local stress/magnetism simultaneously (e.g., correlating Meissner effect with local strain). |
| Quantum Sensing & Metrology | Development of next-generation integrated quantum devices. | VB- centers offer superior stress response compared to NV centers; 2D materials allow seamless heterogeneous integration. |
| Geology and Geophysics | Studying mechanical deformation and paleomagnetism under extreme conditions. | Provides high-resolution, in situ characterization of stress gradients in solid media (like NaCl) at high pressures. |
| 2D Materials Engineering | Characterizing strain and interfacial phenomena in van der Waals heterostructures. | Nanoscale proximity enables imaging of stress and magnetic fields directly at the interface between the sensor and the target material. |
| Microelectronics Manufacturing | Large-scale manufacture of integrated quantum devices. | 2D sensors are compatible with three-dimensional heterogeneous integration techniques. |
View Original Abstract
Pressure serves as a fundamental tuning parameter capable of drastically modifying all properties of matter. The advent of diamond anvil cells (DACs) has enabled a compact and tabletop platform for generating extreme pressure conditions in laboratory settings. However, the limited spatial dimensions and ultrahigh pressures within these environments present significant challenges for conventional spectroscopy techniques. In this work, we integrate optical spin defects within a thin layer of two-dimensional (2D) materials directly into the high-pressure chamber, enabling an in situ quantum sensing platform for mapping local stress and magnetic environments up to 3.5 GPa. Compared to nitrogen-vacancy (NV) centers embedded in diamond anvils, our 2D sensors exhibit around three times stronger response to local stress and provide nanoscale proximity to the target sample in heterogeneous devices. We showcase the versatility of our approach by imaging both stress gradients within the high-pressure chamber and a pressure-driven magnetic phase transition in a room-temperature self-intercalated van der Waals ferromagnet, Cr<sub>1+δ</sub>Te<sub>2</sub>. Our work demonstrates an integrated quantum sensing device for high-pressure experiments, offering potential applications in probing pressure-induced phenomena such as superconductivity, magnetism, and mechanical deformation.