https://doi.org/10.1140/epjqt/s40507-025-00388-5
Research
Quantum diamond microscope method to determine AC susceptibility in micro-magnets
1
Department of Electrical Engineering, Indian Institute of Technology Bombay, 400076, Mumbai, Maharashtra, India
2
Element Six, Harwell, United Kingdom
3
Center of Excellence in Quantum Information, Computing Science and Technology, Indian Institute of Technology Bombay, 400076, Mumbai, Maharashtra, India
4
Center of Excellence in Semiconductor Technologies (SemiX), Indian Institute of Technology Bombay, 400076, Mumbai, Maharashtra, India
Received:
29
March
2025
Accepted:
25
June
2025
Published online:
7
July
2025
AC susceptometry, unlike static susceptometry, offers a deeper insight into magnetic materials. By employing AC susceptibility measurements, one can glean into crucial details regarding magnetic dynamics. Nevertheless, traditional AC susceptometers are constrained to measuring changes in magnetic moments within the range of a few nano-joules per tesla. Additionally, their spatial resolution is severely limited, confining their application to bulk samples only. In this study, we introduce the utilization of a Nitrogen Vacancy (NV) center-based quantum diamond microscope for mapping the magnetic fields resulting from micron-scale ferromagnetic samples under an AC drive field, which can be used for determining AC susceptibility with sufficient additional information about the sample. By employing coherent pulse sequences, we extract the in-phase component of the sample magnetic field from samples within a field of view spanning 70 micro-meters while achieving a resolution of 1 micro-meter. Furthermore, we quantify changes in dipole moment on the order of a femto-joules per tesla induced by excitations at frequencies reaching several hundred kilohertz.
Key words: Nitrogen-vacancy center / Magnetic Susceptibility / Quantum Diamond Microscope / AC Sensing
© The Author(s) 2025
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