Study of two-dimensional mixed state of type-I superconductors

We describe an experimental study of the destruction of superconductivity by current in hollow indium samples. In particular, we determine the destruction current I/sub c/2 of the two-dimensional mixed state and investigate the temperature dependence of the paramagnetic effect in a weak longitudinal magnetic field. In addition, we investigate the mixed state produced on the surface of a bulky cylindrical sample when a strong longitudinal magnetic field is abruptly turned off. Particular attention is paid to the study of the structure produced in a two-dimensional mixed-state layer in the presence of a weak transverse magnetic field. The velocity and the characteristic dimensions of the structure are measured at various values of the temperature and current density in the sample and of the transverse magnetic field