In these severe, high pressure environments, traditional sensor systems usually struggle to operate because of the distance between sensors and the sample, and the relatively weak signals in these sensors.
This work utilizes the atomic-scale thickness of hexagonal boron nitride (hBN) containing boron-vacancy (VB-) centers. Working in 2D like this means the sensors can sit just nanometers from a sample, dramatically improving spatial resolution and sensitivity.
As a result, the team has managed to produce a powerful new tool for capturing nanoscale stress gradients and magnetic transitions in situ.
Accurate high-pressure measurements are essential for studying how materials behave under extreme conditions, with wide-ranging implications in physics, materials science, and geology.
The Study
Using chemical vapor deposition, the team synthesized ~100 nm thick hBN layers with uniformly distributed VB- centers. These layers were then transferred directly onto the culet surface of diamond anvils, positioning them extremely close to the sample chamber inside the DAC.
They used a van der Waals magnet Cr1+δTe2, with a Curie temperature above 330 K, as a sample, placing the material in the DAC chamber with the sensors. The team applied pressures of up to 3.5 GPa and monitored the spin properties of the VB- centers with optically detected magnetic resonance.
Shifts in spin energy levels under varying stress and magnetic conditions allowed the researchers to map stress distributions and detect magnetic phase transitions with nanometer-scale resolution.
First-principles simulations supported the experimental data, predicting how the VB- centers respond to local strain. Additional microscopy and spectroscopic techniques confirmed that the sensors remained structurally and electronically stable under pressure.
Results and Discussion
Data analysis showed that the VB- centers displayed a measurable shift in spin transition frequency of about 43 MHz per GPa, which is roughly three times more sensitive than typical NV centers. This enhanced responsiveness could allow for far more accurate pressure measurements.
The sensors were still able to detect highly localized stress gradients as the pressure inside the DACs increased, especially above one gigapascal, where solid media like NaCl induced non-uniform stresses.
Because of their near-atomic thickness, the hBN sensors were able to pick up subtle variations at the sample surface, details that would typically be lost in bulk measurements.
The sensors also revealed a magnetic phase transition in Cr1+δTe2, shifting from ferromagnetic to paramagnetic under rising pressure. These changes were captured through spin resonance signals, demonstrating the sensors’ effectiveness at tracking both mechanical and magnetic changes at the nanoscale.
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Conclusion
This study demonstrated the potential of 2D quantum sensors in delivering precise, in situ measurements of stress and magnetism inside high pressure chambers. Their ultrathin design enables them to operate right at the sample interface, outperforming conventional NV-based systems limited by distance and orientation.
The sensors' enhanced sensitivity and resolution open new possibilities for studying phenomena like superconductivity, magnetism, and structural phase transitions under extreme conditions. With further improvements in design and pressure range, these platforms could become essential tools for nanoscale exploration in high-pressure physics and beyond.
Journal Reference
He G. et al. (2025). Probing stress and magnetism at high pressures with two-dimensional quantum sensors. Nature Communications 16, 8162. DOI: 10.1038/s41467-025-63535-7, https://www.nature.com/articles/s41467-025-63535-7