Figure 3. Landau–Lifshitz–Gilbert simulations.

(a) Cartoon models representing the simulations of two adjacent iron oxide nanoparticles (IO NPs) of different sizes. The inter-particle distance (L) is 1.0 nm in models C1–C3. The models C4 and C5 are derived from model C3 but with different L of 0.1 and 5.0 nm, respectively. (b–f) Landau–Lifshitz–Gilbert simulation results of the stray field for model C1–C5, respectively. The L is 1 nm (b–d), 0.1 nm (e) and 5.0 nm (f). Colour bars represent log₁₀(H_d) (a.u.), where H_d is the calculated stray field. (g,h) Calculated stray field and stray field gradient of C1–C5 with an out-of-plane distance (d) of 3 nm.