Magnetic particle Force Microscopy is a new take on familiar family of techniques. It is based on scanning probe microscopy, specifically it uses an atomic force microscope setup and since magnets are involved, it is related to magnetic force microscopy. The interesting thing about scanning probe microscopy is the analogies each measurement has to large scale measurement techniques. Since SPM consist of physically moving a probe around a sample, any probe or system of measurement that can be miniaturized, can be turned into a SPM technique. For magnetic systems this has so far consisted of miniaturized versions of fluxgate magnetometer, magnetic resonance imaging/nuclear magnetic resonance, ferromagnetic or electron magnetic resonance, or the magnetic force balance. With all these techniques available to characterize systems magnetically, why do we really need another one and how is it different.
Each one of these measurement techniques is specialized to measure a specific phenomenon, or designed using a certain, often complicated, setup. MPFM overlaps strongly with both MR/FR/ER-FM and Fluxgate-MFM. However the experimental setup is simplified and instead of using a complex measurement setup, it relies on a computationally intensive model in order to reduce the measurement time and complexity and make it suitable to measuring large systems quickly. The aim of MPFM also differs from any of the previous techniques, we are not interested in measuring the magnetic field quantitatively, or the spin resonances in the system whether they be magnetic, electron, or proton, but instead we aim to measure the m-H response curve of the sample. Specifically we are looking at the quantitative m-H response curve of magnetic particles as well as their 3D positions. This measurement is unique among the various techniques available for magnetic systems and there are both large (micrometer +) and small (10’s-100’s of nanometer) systems that can benefit from MPFM.
“Magnetic Particle Imaging with a Cantilever Detector” JW. Alldredge, John Moreland, Journal of Applied Physics 112, 023905 (2012)