A Functional Analytical Model Reveals Demagnetization Effects in Fe-Co-Ni Alloy Single-Domain Magnetic Nanoparticles

This paper establishes a simple analytical formula-based model of magnetization of single-domain magnetic nanoparticles, taking into account the effect of a demagnetizing field. This makes it easier to calculate magnetic induction intensity for magnetic nanoparticles. The magnetization model is used to simulate the magnetic properties of Fe-Co-Ni alloy nanoparticles under various conditions. The results show that the demagnetization field generated by magnetic nanoparticles in an external magnetic field reaches a peak value around 10 nm and decreases as temperature rises. The simplified magnetization model of single-domain magnetic nanoparticles could provide the theoretical basis for single-molecule magnetic immunoassay.