The current-voltage characteristics of high-quality thin tin films, ranging in width from 7 to 50 μm, irradiated by microwave radiation are investigated. The behavior of the critical current Ic and of the maximum current Im for the existence of a stationary flow of the characteristic vortices of the transport current (formation current of the first phase-slip line) is analyzed. The regimes of enhancement and suppression of the currents Ic and Im by a microwave field are studied and analyzed. The criteria for separating films into narrow and wide are established. It is shown that the superconductivity enhancement effect is a general effect and is observed for uniform (narrow films) and nonuniform (wide films) distributions of the superconducting current over the film width.

We present the data of the point contact (PC) Andreev-reflection measurements on the new paramagnetic superconductor Mo3Sb7, which were used for finding the energy gap Δ and upper critical field Hc 2 for this compound. The maximum gap value, reduced to the zero temperature via the Bardeen–Cooper–Schrieffer (BCS) theory, turned out to be  meV, which is slightly smaller than that expected from the BCS theory,  meV. The temperature dependence of the gap obeys the BCS theory approximately. The Hc 2(0) value of about 16.5 kOe was obtained from fitting the experimental data to the conventional H(T) dependence, which is quadratic in temperature. This value is in close agreement with the result from magnetization measurements of 17.2 kOe.

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