THE FORCE BETWEEN A MONOLAYER OF MAGNETIC PARTICLES AND A SUPERCONDUCTOR IN THE MIXED STATE

Abstract

The interaction between a monolayer of fine ferromagnetic particles and a semi-infinite superconductor has been investigated in the mixed state. The frozen and diamagnetic images model was employed to calculate the levitation force as a function of the levitation height as well as the temperature of the monolayer under the zero-field-cooled (ZFC) and the field-cooled (FC) conditions. Results showed the well-known monotonic decrease of the levitation force as a function of the levitation height while it increases rapidly as a function of temperature up to saturation. As a result of the first order approximation used in our calculations in which the interaction was represented by the forces between the magnetic dipoles and their images, the levitation force was dominated by the diamagnetic properties rather than the flux pinning effects of the superconductor for small values of levitation heights compared to the initial field cooling height.