Point-contact tunneling device

A simple point-contact tunneling device for examination of the properties of almost any metal, alloy, or compound of almost any shape is described. The device has a small mass to permit dipping into liquid helium directly from room temperature. The stability and accuracy of the drive mechanism permit it to be used for single-particle superconductive tunneling as well as for Josephson devices, weak links, and metal-metal bridges. Experimental results showing a recording of the drive characteristics of the differential screw, the transition from Josephson weak-link behavior to single particle tunneling for a Nb–I-Vycor (Pb) sample, a well-resolved energy gap for niobium, and the phonon structure of lead are presented.