Takahashi, Y., Miyamachi, T., Ienaga, K., Kawamura, N., Ernst, A., Komori, F.
Orbital selectivity in scanning tunneling microscopy: Distance-dependent tunneling
process observed in iron nitride
Physical Review Letters 116, (5),pp 056802/1-5 (2016)
In scanning tunneling microscopy, orbital selectivity of the tunneling process can make the topographic image dependent on a tip-surface distance. We have found reproducible dependence of the images on the distance for a monatomic layer of iron nitride formed on a Cu(001) surface. Observed atomic images systematically change between a regular dot array and a dimerized structure depending on the tip-surface distance, which turns out to be the only relevant parameter in the image variation. An accompanied change in the weight of Fe-3d local density of states to a tunneling background was detected in dI/dV spectra. These have been attributed to a shift in surface orbitals detected by the tip from the d states to the s/p states with increasing the tip-surface distance, consistent with an orbital assignment from first-principles calculations.
TH-2016-07