Point contact tunnelling apparatus with temperature and magnetic field control

摘要

The design and testing of a new device for point contact tunnelling measurements in superconductors are described. The insert is designed for use with a continuous flow cryostat which allows for a large range of sample temperatures from 1.5 K to room temperature. The use of nonmagnetic parts allows tunnelling measurements to be performed in high magnetic fields. Testing was carried out on a conventional super conductor, Nb, in fields up to 6 T using Nb and Au tips to obtain superconductor-insulator-superconductor and superconductor-insulator-normal metal junctions. In addition, a moderate-T-c oxide superconductor, Ba1-xKxBiO3', was used to obtain temperature and magnetic field dependencies of the energy gap. (C) 1998 Elsevier Science Ltd. All rights reserved. [References: 13]