Enhancement of Superconductivity in Thin Aluminum Films

Abstract

<p> The phenomena of energy gap and transition temperature enhancement have been studied on very thin (35-80 A° ) aluminum films, using the technique of electron tunneling through a thin insulating barrier. Transition temperatures as high as 2.16°K have been measured, and the corresponding measured energy gaps are found to be unique. In addition, these thin superconducting films exhibit stable transition temperatures when held in a vacuum. However, upon breaking vacuum, oxide growth occurs, and the tunneling barrier becomes impenetrable. Existing theories proposed to explain the observed enhancements, are discussed in the light of present accumulated experimental evidence. However, it is found that none are capable of explaining adequately the observed enhancements. </p>