Discovery of low‐temperature metastable state in amorphous bismuth—hydrogen systems

Abstract Electric and superconducting properties of Bi films condensed in the H 2 atmosphere ( p H 2 = = 5 × 10 −6 to 2 × 10 −5 Torr) onto a liquid‐helium‐cooled substrate are studied. The dissolved hydrogen is found to increase essentially the resistivity Q , to suppress T c and raise the amorphous—crystalline transition temperature T ac . If p H 2 exceeds some critical values, the films prepared are in the metastable phase, a‐Bi(H), highly saturated with hydrogen. At about 5 K this phase transforms into ordinary, also metastable, amorphous Bi, which results in a sharp decrease of the normal resistance (down to two orders of magnitude) and a T c rise (up to 2 K). In a number of cases this transition proceeds as a heating‐induced jump from the resistive to the superconducting state. The properties of pure and hydrogen‐saturated Bi films are thoroughly compared. The results obtained are discussed on the base of the up‐to‐date knowledge.

Перевод пока недоступен