The nano-mechanics and magnetic properties of high moment synthetic antiferromagnetic particles

With nanomagnets increasingly being used and proposed as functional units for in vivo applications, it is vital to understand how to optimize their structure, geometry, and size, and their responses to electromagnetic stimulation. Herein, we predicate how to do so for synthetic antiferromagnetic structures that are subjected to external magnetic control. Because the structures are on the scale of biological entities, interactions with cells and molecular constituents can be extreme and careful design must be undertaken to avoid detrimental effects. Thus, the magnetic responses of multilayers, as demonstrated in experiments by Koh et al. [e.g., Hu et al., Adv. Mater. 20, 1479 (2008) and Koh et al., J. Appl. Phys. 107, 09B522 (2010)], are understood using a fully dynamical investigation based on Landau–Lifshitz–Gilbert equations. We find that during the fabrication of the structures the axial positions of the nanomagnets become offset from each other, leading to the characteristic magnetic hysteresis shapes witnessed. We then find the magnetic nano-mechanical forces generated by such structures.