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Complete Eigenvalue Spectrum for the Nucleation in a Ferromagnetic Prolate Spheroid

1963; American Institute of Physics; Volume: 131; Issue: 4 Linguagem: Inglês

10.1103/physrev.131.1478

1536-6065

Amikam Aharoni,

Electromagnetic Scattering and Analysis

Curling, coherent rotation, and an appropriately defined buckling are proved to be the only three modes which might yield numerically smallest nucleation field in ellipsoids of revolution (both prolate and oblate), all the other possible eigenmodes yielding more negative nucleation fields. A lower bound for the buckling mode in a prolate spheroid is calculated by neglecting the transverse magnetostatic self-energy. In contra-distinction to the limiting case of an infinite circular cylinder, in which coherent rotation never takes place, it is found that for prolate spheroid of any finite elongation, coherent rotation is the lowest eigenmode for small enough radii. Upper and lower bounds are given for the critical radius under which coherent rotation takes place, as a function of the elongation. Buckling is seen to take place at most in a rather small region of sizes between curling and coherent rotation.