Additional imaging mode
MFM and PFM
This optional upgrade extends the QSM’s imaging capabilities to include MFM and PFM modes, transforming it into a full-stack magnetometer capable of multiple complementary magnetic inspection techniques, including NV, MOKE, PFM, and MFM. A dedicated beam-bounce AFM head can accommodate both magnetic and conductive probes, featuring alignment grooves that ensure reproducible tip placement within a few micrometers. This design enables rapid and precise switching between one tip and the other, with the new tip positioned within a few micrometers of the previous scan area. As a result, imaging the same region with both NV and MFM or PFM can be completed in just a few minutes.
MFM – Magnetic Force Microscopy
MFM is a variant of atomic force microscopy in which a magnetized tip senses the stray magnetic fields of a sample. The tip is mounted on a flexible cantilever, which bends in response to magnetic forces. In a beam-bounce AFM setup, a laser reflects off the cantilever onto a photodiode; the cantilever deflection is then determined from the displacement of the laser spot on the diode. This allows quantitative mapping of the magnetic forces above the sample surface, complementing NV magnetometry by providing additional contrast and structural information.
PFM – Piezo Force Microscopy
PFM is a scanning probe technique that maps ferroelectric domains by detecting the mechanical response of a material to an applied electric field. Integrating PFM alongside NV magnetometry is particularly valuable for BiFeO₃ (BFO) and other multiferroics, as it allows simultaneous imaging of ferroelectric and magnetic order. This combined capability enables direct correlation between magnetic textures and ferroelectric domains, providing a more complete understanding of the magnetoelectric coupling and domain dynamics in these complex materials.
KPFM – Kelvin Probe Force Microscopy
KPFM is a scanning probe technique that maps the local surface potential and work function of a sample by measuring the electrostatic force between a conductive tip and the surface. The tip is oscillated at resonance in a dynamic non-contact mode, while an AC voltage on the sample modulates the electrostatic force and a DC bias nulls it; that compensating bias gives the contact potential difference at every point. Shown here is a KPFM scan of a gold grating on silicon, resolving the work function contrast between metal and substrate. Alongside NV magnetometry, KPFM adds an electronic channel to the same scan area, linking local charge and doping to the magnetic texture.