Abstract Room‐temperature (RT) 2D van der Waals (vdW) ferromagnets hold immense promise for next‐generation spintronic devices for information storage and processing. To achieve high‐density energy‐efficient spintronic devices, it is essential to understand the local magnetic properties of RT 2D vdW magnets. In this work, noninvasive in situ stray field detection is realized in vdW‐layered ferromagnet Fe 3 GaTe 2 using divacancy spins quantum sensor in silicon carbide (SiC) at RT. The structural features and magnetic properties of the Fe 3 GaTe 2 are characterized utilizing X‐ray diffraction, scanning tsransmission electron microscopy, Raman spectrum, magnetization, and magneto‐transport measurements. Further detailed analysis of temperature‐ and magnetic field‐dependent optically detected magnetic resonances of the PL6 divacancy near the Fe 3 GaTe 2 reveal that, the Curie temperature ( T c ) of Fe 3 GaTe 2 is ∼360 K, and the magnetization increases with external magnetic fields. Additionally, spin relaxometry technology is employed to probe the magnetic fluctuations of Fe 3 GaTe 2 , revealing a peak in the spin relaxation rate around the T c . These experiments give insights into the intriguing local magnetic properties of 2D vdW RT ferromagnet Fe 3 GaTe 2 and pave the way for the application of SiC quantum sensors in noninvasive in situ stray field detection of related 2D vdW magnets.
