Magnetization Controlled Superconductivity in a Film with Magnetic Dots
  We consider a superconducting film with Magnetic Dots Array (MDA) placed on it. Magnetic moments of these dots are supposed to be normal to the film and strong enough to create vortices in the superconducting film. Magnetic interaction between dots is negligible. Below the superconducting transition temperature of the film in zero magnetic field the MDA with randomly magnetized dots produces resistive state of the film. Paradoxically, in a finite magnetic field the film with MDA is superconductive. 
Igor F.Lyuksyutov and Valery Pokrovsky