Influence of hydrogen impurities on the electrical and superconducting properties of disordered lead films

The electrical and superconducting properties of lead films (thickness 70−350 Å) deposited onto liquid-helium-cooled substrate in a hydrogen atmosphere (at pressures pH2 = 10−6−10−4 torr) have been studied. We have found that as the hydrogen content increases, disordering of the lattice of the films ensues and is accompanied by an increase in the residual resistivity (until signs of weak localization of electrons appear) and a lowering of the superconducting transition temperature Tc. The decrease in Tc under the influence of the disordering is described by the expression ΔTc ∽ In2R□ (R□ is the resistance of a square section of the film). The results of these studies and the data from previous investigations suggest that during hydrogenation of nontransition metals by means of codeposition of metal and hydrogen the principal mechanism by which hydrogen affects Tc is associated with lattice distortions.

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