Magnetic Nanoparticles: A Subject for Both Fundamental Research and Applications

Figure 11

(a) Calculated spin configuration at 𝐻=0 for a cross-section of a NiFe₂O₄ particle with diameter 2.5 nm. Circles indicate extremely canted orientations. Reproduced with permission from Kodama et al. [92] © 1996, APS. (b) Temperature dependence of 𝜒^′ and 𝜒^′′ (solid and open symbols, resp.) of NiO particles with mean diameter 6.5 nm under an 𝑎𝑐 field of 𝐻₀=10 Oe, measured at frequencies 10Hz≤𝑓≤10kHz with 𝜒^′ peaking at 𝑇_𝑔=15.9 K as 𝑓→0. The inset shows the high temperature region with 𝜒^′ peaking at 𝑇_𝐵≈85 K. Reproduced with permission from Winkler et al. [95] © 2008, IOP Publishing.

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