Comment on “London model for the levitation force between a horizontally oriented point magnetic dipole and superconducting sphere”

D. Palaniappan

doi:10.1103/PhysRevB.75.016502

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Comment on “London model for the levitation force between a horizontally oriented point magnetic dipole and superconducting sphere”

D. Palaniappan

DOI 10.1103/PhysRevB.75.016502 · Physical Review B

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Abstract

The levitation force due to a horizontally oriented point magnetic dipole placed in front of a superconducting sphere is calculated and is shown to be different from the result given recently by Coffey [Phys. Rev. B 65, 214524 (2002)]. The present calculation for the levitation force is based on the formulas developed long ago for an equivalent Neumann boundary value problem in hydrodynamics. The result derived here demonstrates that the value of the levitation force for a horizontally oriented dipole lies between one-fourth and one-half the value of the configuration with a radially oriented point dipole, thus providing upper and lower bounds for the levitation force due to a tangentially oriented magnetic dipole.