Direct Detection of the Magnetic Force and Field Coupling of Electronic Spins Using Photoinduced Magnetic Force Microscopy.

The intrinsic spin of the electron and its associated magnetic moment can provide insights into spintronics. However, the interaction is extremely weak, as is the case with the coupling between an electron's spin and a magnetic field, and it poses significant experimental challenges. Here we demonstrate the direct measurement of polarized single NV centers and their spin-spin coupling behaviors in diamond. By using photoinduced magnetic force microscopy, we obtain the extremely weak magnetic force coupling originating from the electron spin. The polarized spin state of NV centers, transitioning from |0⟩ to |±1⟩, and their corresponding Zeeman effect can be characterized through their interaction with a magnetic tip. The result presents an advancement in achieving electron spin measurements by magnetic force, avoiding the need for manufacturing conductive substrates. This facilitates a better understanding and control of electron spin to novel electronic states for future quantum technologies.