Temperature-dependent secondary electron yield from ion bombardment of gold and copper oxide superconductors

Abstract

First measurements on the ion-induced kinetic secondary-electron emission have been performed with low beam current densities in the low target temperature range $70 \mathrm{K}<T<300 \mathrm{K}$ under good vacuum conditions ($p\ensuremath{\approx}5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}7}$ Pa) from sputter-cleaned Au foils (1000 \AA{}) and from Y${\mathrm{Ba}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$. The secondary-electron yield $\ensuremath{\gamma}$ decreases with decreasing temperature of Au and Y${\mathrm{Ba}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$ targets. This is in contrast to the expectations based on previous experiments and theoretical considerations. In the case of Y${\mathrm{Ba}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$, a strong enhancement of $\ensuremath{\gamma}$ below the superconducting transition temperature ${T}_{c}$ is observed.