Fluxoid Pinning in Superconductors by a Periodic Array of Magnetic Particles

We assume a two-dimensional array of ferromagnetic particles on the surface of a thin type-II superconductor in a transverse magnetic field. With a particle at the center of each fluxoid, the pinning force P and critical current increase Delta J(c) due to the particles are calculated. General expressions without arbitrary parameters are given for P and Delta J(c) as functions of magnetic field strength and the characteristics of the superconductor and the particles. For broad ranges of conditions values of P and Delta J(c) greater than 10(-7) dyn and 10(5) A/cm(2) result and for certain physically realistic sets of conditions, P > 10(-6) dyn and Delta J(c) > 10(6) A/cm(2) are predicted. The above effects should be readily observable. An experiment for setting up the assumed conditions is proposed and discussed in some detail.