The electrical resistivity and superconducting transition temperatures are studied as a function of hydrogen content on two series of Nb-Ta superlattices grown by molecular-beam epitaxy with modulation wavelengths of 20 and 85 A. Hydrogen enhances the resistivity of the structures which, in extreme cases, leads to a logarithmic temperature dependence at very low temperatures. All structures undergo a transition to a superconducting state, but with increasing hydrogen content the transition temperatures are continuously depressed. This behavior differs from that of bulk hydrogenated Nb and Ta systems and is believed to have its origin in the epitaxial constraints imposed by the substrate on these single-crystalline superlattices.
ASJC Scopus subject areas
- Condensed Matter Physics