Shape of the nuclear magnetic resonance line in type-II superconductors with an irregular of Abrikosov vortex lattice.

The NMR (EPR) line shape in type-II superconductors has been constructed with allowance for a change in the nonuniform magnetic field of an irregular vortex lattice near the surface of a superconductor. The NMR (EPR) line shape is shown to change as a function of the irregularity of the vortex lattice rather that being simply broadened. This change is related to a lowering of the local symmetry of the irregular vortex lattice in the superconductor. This circumstance can substantially change the conclusions regarding the vortex-lattice type and the superconductor parameters that are usually drawn from the magnetic resonance line shape.