Surface impedance of a type-II superconductor in dc magnetic fields parallel and tilted to the superconductor border

The surface impedance Z of type-II superconductors in the mixed state has been studied taking into account magnetic permeability of the vortex lattice for an arbitrary orientation of the dc magnetic field with respect to the superconductor border. For the dc field parallel to the border the Bean-Livingston barrier in the vortex-free region suppresses the entry and the exit of vortices from the superconductor interior. For this case the theory predicts surface-induced suppression of the ac losses (the surface resistance 3/2 instead of 1/2). We have found the angle between the dc magnetic field and the superconductor surface at which the crossover occurs from the usual electrodynamic response to that governed by the Bean-Livingston barrier.