Exact cloaking of uniform magnetic fields with a superconductor-magnetic   bilayer
  The experimental realization of cloaks for electromagnetic fields has been possible only in reduced schemes because of extreme material conditions required in exact cloaks. Here we analytically demonstrate that a simple arrangement of two concentric homogeneous and isotropic layers with different permeabilities can keep a uniform externally applied magnetic field unperturbed. If the inner layer is superconducting, the device prevents exterior fields from entering an enclosed region, which represents a case for an exact cloaking of uniform fields. When the applied field is inhomogeneous the cloaking property is reduced but may be optimized by changing the thickness of the layers. 
Carles Navau, Jordi Prat-Camps and Alvaro Sanchez
cond-mat.supr-con