Abstract
The apparent barrier height , that is, the rate of change of the logarithm of the conductance with tip-sample separation in a scanning tunneling microscope (STM), has been measured for Ni, Pt, and Au single crystal surfaces. The results show that is constant until point contact is reached rather than decreasing at small tunneling gap distances, as previously reported. The findings for can be accounted for theoretically by including the relaxations of the tip-surface junction in an STM due to the strong adhesive forces at close proximity. These relaxation effects are shown also to be generally relevant under imaging conditions at metal surfaces.
- Received 3 November 1995
DOI:https://doi.org/10.1103/PhysRevLett.76.1485
©1996 American Physical Society