AVS 45th International Symposium
    Nanometer-scale Science and Technology Division Wednesday Sessions
       Session NS+AS-WeM

Paper NS+AS-WeM8
Conductance and Force at an Atomically Defined Junction

Wednesday, November 4, 1998, 10:40 am, Room 321/322/323

Session: Innovative Force, Near-Field Optics, and Tunneling Measurements
Presenter: G. Cross, McGill University, Canada
Authors: G. Cross, McGill University, Canada
A. Schirmeisen, McGill University, Canada
A. Stalder, McGill University, Canada
P. Grütter, McGill University, Canada
U. Dürig, IBM Research Division, Switzerland
Correspondent: Click to Email
We have simultaneously measured conductivity and force between an atomically defined tip and atomically flat sample in UHV. The sharp metal tips are manipulated and characterized on an atomic scale both before and after the sample approach by field ion microscopy (FIM). Conductivity over a large range is obtained by a multidecade nonlinear current amplifier,@footnote 1@ while simultaneously forces between the tip and sample are measured by an in-situ differential interferometer with sub-nN force sensitivity. We report on the conductivity and force vs. tip-sample separation relationships for specific atomic tip geometry. In particular, we have examined the precontact regime characterized by short-ranged attractive forces. In this regime, we find that for a trimer W tip approaching an Au(111) surface, the square of the force depends linearly on conductivity. This can be understood if one assumes that both tunneling and adhesion quantum mechanical exchange interactions are due to overlap of tip and sample wavefunctions.@footnote 2@ @FootnoteText@ @footnote 1@U. Dürig, L. Novotny, B. Michel, A. Stalder , Rev. Sci. Instr. 68, 3814 (1997) @footnote 2@C. Chen, J. Phys. Cond. Matter 3, 1227 (1991)