Probing boron vacancy defects in hBN via single spin relaxometry

Area of Science:

• Quantum physics
• Materials science
• Nanotechnology

Background:

• Spin defects in solids are promising for quantum sensing and memory.
• Nitrogen-vacancy (NV) centers in diamond are well-established quantum sensors.
• Boron vacancy ($V_B^{-}$) centers in hexagonal boron nitride (hBN) are emerging 2D spin systems.

Purpose of the Study:

• To develop a method for detecting and spatially mapping spin defects, specifically $V_B^{-}$ centers in hBN, using NV centers.
• To demonstrate indirect readout of spin properties without optical excitation of the target defect.
• To establish NV centers as versatile probes for characterizing other spin systems.

Main Methods:

• Integration of a single NV center with scanning probe microscopy.
• Indirect detection of $V_B^{-}$ electron spin resonance via changes in NV center's spin relaxation time (T₁).
• Utilizing cross-relaxation between NV and $V_B^{-}$ ensembles for nanoscale mapping.

Main Results:

• Successful indirect detection and nanoscale mapping of $V_B^{-}$ centers in hBN.
• Quantitative mapping of defect densities beyond the optical diffraction limit.
• Resolution of hyperfine splitting in isotopically enriched h¹⁰B¹⁵N.

Conclusions:

• NV centers can serve as versatile probes for characterizing inaccessible spin defects in various materials (3D and 2D).
• The developed method bypasses the need for optical excitation/fluorescence detection of the target spin defect.
• This approach advances nanoscale quantum sensing and characterization of quantum materials.