Measured the tunneling characteristics of a series of Al-oxide-(Ag//1// minus //xEr//x)Pb proximity effect sandwiches for normal metal thicknesses ranging from 500 A to 3000 A and parallel magnetic fields of 0-1000 gauss. Second derivative characteristics (d**2V/dI**2) reveal the Pb phonon structure through electron interference effects and also reveal structure at the Ag phonon frequencies. Application of a magnetic field less than the critical field of the sandwich reduces the Ag phonon structure. Introduction of impurities reduces the interferences effects with little effect on the Ag phonon structure. Thus the two contributions to the tunneling characteristics can be separated. Comparison with the theory of McMillan and Rowell then allows determination of V//F. Comparison of the theoretical and experimental curves for the interference term shows a frequency dependent mean free path from phonon emission and allows an independent measure of the electron-phonon coupling in the normal metal.
|Original language||English (US)|
|Number of pages||5|
|Journal||J Phys (Paris)|
|State||Published - 1978|
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