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We investigate the spin-lattice relaxation of the dipolar order in $^{1}\mathrm{H}$ NMR in hydrogenated amorphous silicon $(a\text{\ensuremath{-}}\mathrm{Si}:\mathrm{H})$. We find that the relaxation is dominated by the cross relaxation between the hydrogen nuclei and the paramagnetic states. The relaxation is inhomogeneous, and can be described as a stretched exponential function. We proposed a possible mechanism for this relaxation. This mechanism applies to a rather broad range of paramagnetic states, including the deep neutral defects (dangling bonds), the light-induced metastable defects, the defects created by doping, and the singly occupied, localized band-tail states populated by light at low temperatures. The cross relaxation is only sensitive to the bulk spin density, and the surface spins have a negligible effect on the relaxation.

For the first time, structure has been found in the electron tunneling characteristics of a metal-oxide-semiconductor tunnel junction of an amorphous semiconductor. In the present study the amorphous semiconductor is phosporus-doped hydrogenated amorphous silicon. The results have been analyzed to determine the surface density of states over part of the forbidden gap. The basic features of the density-of-states distribution are in agreement with the results of field-effect measurements reported for this material.

The magnetic-field dependence of the penetration of radio-frequency fields has been measured in type-II superconductors. We discuss information obtained concerning the mixed state, the superconducting surface sheath, and superconducting cylindrical thin films. Some of the results, such as structure near ${H}_{c2}$, are interpreted in terms of vortex motion and effects of the sheath. Results pertaining to the sheath are compared with the calculations of Fink and Kessinger and of Maki. Other results in the mixed state are related to surface impedance calculations of Maki and of Caroli and Maki, based on the microscopic theory. Penetration depth measurements in the films agree better with a naive model than with Pincus's theory.