Integrated flexible microwave device for magnetic material scanning using nitrogen-vacancy center

We design a flexible microwave transmission line based on a splitting-combining structure and integrate it with a fiber-diamond probe to form a unified quantum probe, providing a resonant driving microwave magnetic field. This device utilizes a polyimide (PI) flexible substrate, which is conformable. A through-hole is designed at the center of the ring to accommodate fiber insertion, enabling the sensing unit to approach the sample under test. Experimental results demonstrate that the device achieves a 394 MHz bandwidth, with a microwave efficiency of $4.64\mathrm{G}/\sqrt{\mathrm{W}}$, balancing broadband with a strong near-field microwave magnetic field. Finally, we characterize the spatial distributions of the static magnetic-field magnitude and the angle between the static magnetic field and the selected NV axis on the surface of the kagome magnet TmMn₆Sn₆, demonstrating the application potential of the proposed probe for magnetic-material characterization.