Measurement of Local Density of States by Scanning Tunneling Spectroscopy at Low Temperature

A scanning tunneling microscope (STM) with a capability of spectroscopic measurement for operation for 300 K to 1.2 K was constructed. Measurements of the current-voltage characteristics (I-V's) were performed on 2H-NbSe2 and a high-T c superconductor Y-Ba-Cu-O. Spatial variations in the local density of states (LDOS) relevant to the low temperature phases, CDW and superconductivity, were extracted from data statistics.