Studying the bulk band structure of niobium by scanning tunneling spectroscopy

Characteristic features of the bulk band structure of niobium were verified by scanning tunneling spectroscopy (STS). Two different techniques were employed: measurement of standard I–V curves carried out at constant tip–sample separation as well as of Z–V characteristics obtained at constant tunneling current allowing to extend the accessible energy range. Within the range from −5 to +5 eV, the local density of states (LDOS) as determined by STS reveals features which can be attributed to critical points of the theoretically calculated bulk band structure of Nb. The agreement of the STS spectra with the calculated density of states as well as with published photoelectron-spectroscopy data is remarkable.