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klopjob
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Homework Statement
We have a very thin plate of single crystalline Ni (fcc). The plane of the plate corresponds to the (001)-plane of the crystal. The crystal has a quadratic shape and is cut so that the edges corresponds to the crystallographic [110]-directions. The shape anisotropy makes the domain magnetization lie in the (001)-plane. The first shape anisotropy constant K1 is negative. Which are the easy directions of magnetization in the crystal?
The Attempt at a Solution
The key sheet says: Since K1 is negative, it implies the easy directions are of type [110]. The literature and http://en.wikipedia.org/wiki/Magnetocrystalline_anisotropy" on the other hand clearly says the easy directions are of type [100] for K1>0 and [111] for K1<0 if the second anisotropy constant K2 is assumed to be zero. Then why isn't [111] the easy direction in this case? Is it simply because it doesn't lie in the (001)-plane? How do we go from here to say that the [110] types are the easy direction, is it a coincidence this is the same as the crystal edges? Furthermore, can we really say these are the easy and not 'medium' directions?
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