Superparamagnetism magnetic moments variations

Magnetic properties of nanoparticles of transition metals such as Co, Ni show marked variations with size. It is well known that in the nanometric domain, the coercivity of the particles tends to zero. 23 Thus, the nanocrystals behave as superparamagnets with no associated coercivity or retentivity. The blocking temperature which marks the onset of this superparamagnetism also increases with the nanocrystal size. Further, the magnetic moment per atom is seen to increase as the size of a particle decreases 25 (see Figure 7). 

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