MFM measures magnetic domain structures by detecting variations in magnetic forces between a magnetized tip and sample surface, allowing visualization of nanoscale magnetic characterization.​

Unlike conventional AFM that measures surface topography through short-range forces, MFM detects long-range magnetic interactions between an AFM tip and the sample surface. A magnetically coated cantilever is oscillated near its resonant frequency while scanning the sample, and magnetic forces from the sample induce phase or frequency shifts, which are recorded as the MFM signal.

Park Systems’ MFM offers two measurement modes to analyze magnetic domains with high flexibility and precision: ​Amplitude Modulation (AM)-MFM and Frequency Modulation (FM)-MFM.​

In AM-MFM, both the first height scan and the second lift scan use amplitude modulation. The magnetic force signal is detected as changes in oscillation amplitude or phase during the lift scan. This approach is straightforward and suitable for general magnetic contrast imaging. It is recommended to maintain a lift height greater than 30 nm to minimize crosstalk from surface features.​

​ In FM-MFM, while the first height scan still uses amplitude modulation to record topography, the second lift scan switches to frequency modulation to detect magnetic force gradients directly as frequency shifts. This results in improved sensitivity and higher spatial resolution. In this mode, a lower lift height (typically less than 10 nm) is recommended to enhance resolution and magnetic contrast.​

2205 stainless steel has a balanced microstructure of both austenite and ferrite phases. Unlike fully austenitic stainless steels, which are non-magnetic, it contains a significant amount of ferrite making it partially magnetic. MFM can be used to analyze 2205 stainless steel by mapping its magnetic domains, revealing variations in ferrite distribution and phase transformation effects.

GdFe is a ferrimagnetic alloy composed of gadolinium and iron, where Gd and Fe magnetic moments are aligned antiparallel, resulting in unique magnetic properties like high coercivity and tunable magnetization.​ MFM enables imaging of magnetic domains and mapping of the domain wall structure in GdFe by detecting phase or frequency shifts induced by magnetic forces from the sample.

MFM integrated with a Field Switchable MFG is crucial for in-situ characterization of magnetic materials. The changing domain structure of Pt/Co thin films on hBN flakes is clearly visualized by MFM phase images under increasing out-of-plane fields 60 G to 130 G, demonstrating the system's capability to study field-dependent magnetic behavior.

MFM phase images capture the complex domain structure changes occurring in the permalloy sample as an in-plane magnetic field is applied. As the field increases from a low value of 10.9 G up to 46 G via intermediate steps like 35.1 G and 34.7 G, the rearrangement and deformation of the domain walls are clearly observed.

The MFM Phase images clearly demonstrate how the magnetic properties of the patterned structure change dramatically based on the direction of the applied 2,000 G field. By acquiring MFM phase images under zero field, 2,000 G in-plane, and 2,000 G out-of-plane field conditions, the results reveal how the external magnetic field direction and magnitude influence the magnetic domain configurations at the nanoscale, confirming the Field Switchable MFG's capability to control and study complex spin configurations in nanoscale devices.