Magnetic sensing: Imaging power electronics; hexagonal boron nitride; nuclear spin microscopy.
Researchers from the Institute of Science Tokyo, Harvard University, and Hitachi used diamond quantum sensors to analyze the magnetization response of soft magnetic materials used in power electronics.
The method can simultaneously image both the amplitude and phase of AC stray fields over a wide frequency range up to 2.3 MHz. It uses a diamond quantum sensor with nitrogen-vacancy centers coupled with two new protocols, Qubit Frequency Tracking (Qurack) for kHz and quantum heterodyne (Qdyne) imaging for MHz frequencies.
The researchers used it to map stray magnetic fields from CoFeB–SiO2 thin films used in high-frequency inductors. They observed that the films exhibited near-zero phase delay up to 2.3 MHz and that energy loss depends on the material’s magnetic anisotropy.
“Simultaneous imaging of the amplitude and phase of AC magnetic fields across a broad frequency range offers numerous potential applications in power electronics, electromagnets, non-volatile memory, and spintronics technologies,” said Mutsuko Hatano, a professor from the School of Engineering at the Institute of Science Tokyo, in a press release. “Qurack’s performance can be enhanced by adopting high-performance signal generators to extend its amplitude range, whereas optimizing spin coherence time and microwave control speed would broaden Qdyne’s frequency detection range.” [1]
Researchers from the University of Cambridge, Hitachi, Australian National University, University of Technology Sydney, and University of Oxford used spin defects in hexagonal boron nitride (hBN) as room-temperature, multi-axis sensors capable of detecting vectorial magnetic field at the nanoscale.
Using optically detected magnetic resonance (ODMR), the team investigated how atomic-scale defects in the hBN lattice fluoresce in response to variations in a magnetic field. “ODMR isn’t a new technique – but what we have shown is that probes built using the hBN platform would allow this technique to be applied in a variety of new situations. It’s exciting because it opens the door to imaging magnetic phenomena and nanomaterials in a way we couldn’t before,” said Simone Eizagirre Barker, a researcher at Cambridge’s Cavendish Laboratory, in a statement.
“The 2D nature of the host material also opens exciting new possibilities for using this sensor,” added Hannah Stern, associate professor of materials at the University of Oxford, in a statement. “For example, the spatial resolution for this technique is determined by the distance between the sample and sensor. With an atomically-thin material, we can potentially realize atomic scale spatial mapping of magnetic field.” [2]
Researchers at the Technical University of Munich and University of Mainz developed a new type of microscopy based on quantum sensors. A kind of magnetic resonance imaging (MRI), nuclear spin microscopy enables visualization of magnetic signals of nuclear magnetic resonance (NMR) by converting them into light.
With a resolution of ten micrometers, the microscope uses a nitrogen-vacancy centers in diamond as a quantum sensor for NMR signals. When irradiated with laser light, the diamond generates a fluorescent signal containing the magnetic resonance signal’s information, which is then recorded with a high-speed camera.
Aside from applications in medical diagnostics and pharmaceutical research, it has potential to be used in materials science for analyzing the chemical composition of thin-film materials or catalysts. [3]
[1] Kitagawa, R., Nakatsuka, A., Kohashi, T. et al. Imaging AC magnetization response of soft magnetic thin films using diamond quantum sensors. Commun Mater 6, 104 (2025). https://doi.org/10.1038/s43246-025-00812-4
[2] M. Gilardoni, C., Eizagirre Barker, S., Curtin, C.L. et al. A single spin in hexagonal boron nitride for vectorial quantum magnetometry. Nat Commun 16, 4947 (2025). https://doi.org/10.1038/s41467-025-59642-0
[3] Briegel, K.D., von Grafenstein, N.R., Draeger, J.C. et al. Optical widefield nuclear magnetic resonance microscopy. Nat Commun 16, 1281 (2025). https://doi.org/10.1038/s41467-024-55003-5
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