Zur Supraleitung von Doppelschichten aus Ag/Sn

Superimposed films of Ag and Sn are produced on suitable conditions of condensation, so that diffusion between the layers is prevented (the condensation temperatures of Ag and Sn are 320 ?K and 150 ?K, respectively). Immediately after condensation the films are cooled to liquid helium temperature, and the transition temperatures of superconductivity are measured. These values are in agreement with a phenomenological theory of P. and R.Hilsch for sufficient thick films. Resistance measurements indicate that an alloy of Ag and Sn is formed above 280 ?K. There is only a small shift of transition temperature caused by the alloying process.