Figure 1: Temperature dependence of electric resistance in polycrystals of when for different magnetic fields at “big” operating current (1 mA). Fields in are put at corresponding curves. On inset: magnetoresistance of the sample at fixed temperature ( K,  mA). The unusual dependence of resistance from magnetic field (the inset to Figure 1) is that varies with field nonmonotonically, demonstrating negative magnetoresistive effect: at first resistance increases and then decreases sharply down to —the value of resistance in the normal state just above the superconducting transition. The maximum value of resistance depends on temperature and at low temperatures can exceed for several orders of magnitude.