 Interactions between magnetic nanoparticles can have a significant effect on their properties. When these particles are aggregated into larger clusters, they can form a collective state which resembles a spin glass. This collective state suppresses superparamagnetism resulting in slower relaxation times. Additionally, exchange interactions between nanoparticles with different orientations of their easy axis can cause them to rotate, changing the direction of their magnetization. This article was authored by Steen Morup, Michael Faut Hansen, and Catherine Franson.