  The recent theoretical study on the multilayer-coating model published in
Applied Physics Letters [1] is reviewed. Magnetic-field attenuation behavior in
a multilayer coating model is different from a semi-infinite superconductor and
a superconducting thin film. This difference causes that of the
vortex-penetration field at which the Bean-Livingston surface barrier
disappears. A material with smaller penetration depth, such as a pure Nb, is
preferable as the substrate for pushing up the vortex-penetration field of the
superconductor layer. The field limit of the whole structure of the multilayer
coating model is limited not only by the vortex-penetration field of the
superconductor layer, but also by that of the substrate. Appropriate
thicknesses of superconductor and insulator layers can be extracted from
contour plots of the field limit of the multilayer coating model given in
Ref.[1].
