Effect of high-temperature heat treatment on penetration depth of superconducting niobium

Abstract

A discussion is given of the change in penetration depth λ at the surface of niobium with various heat treatments and of the causes of the large changes in λ. In particular, the distribution of oxygen in from the sample surface is discussed, along with the thermal faceting caused by heating niobium to high temperatures at pressures near 10−6 Torr.