Dear Mekala,
Here are several interrelations I could add:
1) Thermal fluctuations of the magnetic moment will influence the coercivity if thermal energy per one particle is comparable with the energetic barrier separating the energetic minima.
2) Increase in particle size will change the mechanism of magnetization reversal, and thus the coercivity value: coherent rotation (Stoner-Wohlfarth) -> magnetization reversal via nonhomogenious state (curling, fanning, etc.)-> magnetization reversal via domain walls motion (typicall for the bulk ferromagnets).
3) Surface anisotropy contribution, which could play a significant role in small particles where the surface to volume ratio is considerable, will also scaled with particle size, and thus will influence on coercivity.
Dear Lekala,
there is - or I should better write: there are. It is not quite simple. One reason is that among other things it depends on the mode of magnetization reversal, which itself depends on characteristic magnetic material properties and (their relation to) particle size.
in order to get yourself started, you should pick a good magnetism textbook which covers particles or particulate media to some extent. one such book i like (not on all topics it covers, though) is O'handleys "Modern Magnetic Materials" (Wiley).
If you can be more specific with your question (e.g. specific material or category of material, specific size range) then it may be possible to help you more specifically, too.
Yes. And to Fauth's answer I would like to add the shape effect that introduces the shape anisotropy. In brief. The shape of your magnetic particle has a its own demagnetization field and it matters along what direction you are considering Hc. For example, a nanorod (long and tall) will have small demagnetization along the long axis and you may see no hysteresis effect along the perpendicular direction to the long axis. In the same way a round nanoparticle will show same Hc on any axis you measure it at. My answer, I know, is an oversimplification but hopefully gives you the feel of some of the variable in play. Cheers.
Dear Mekala,
Here are several interrelations I could add:
1) Thermal fluctuations of the magnetic moment will influence the coercivity if thermal energy per one particle is comparable with the energetic barrier separating the energetic minima.
2) Increase in particle size will change the mechanism of magnetization reversal, and thus the coercivity value: coherent rotation (Stoner-Wohlfarth) -> magnetization reversal via nonhomogenious state (curling, fanning, etc.)-> magnetization reversal via domain walls motion (typicall for the bulk ferromagnets).
3) Surface anisotropy contribution, which could play a significant role in small particles where the surface to volume ratio is considerable, will also scaled with particle size, and thus will influence on coercivity.
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