STM study of multiband superconductivity in NbSe2 using a superconducting tip

We present a method to produce superconducting tips to be used in scanning tunneling micro scopy/spectroscopy experiments. We use these tips to investigate the evolution of the electronic density of states of NbSe2 from 0.3 K up to its critical temperature (7.2 K). The use of a superconducting tip (Pb) as counterelectrode provides an enhancement of the different features related to the DOS of NbSe2 in the tunneling conductance curves, along all the studied thermal range. The analysis of the experimental results gives evidence of the presence of multiband superconductivity in NbSe2. (C) 2004 Elsevier B.V. All rights reserved.