Direct observation of surface chemical order by scanning tunneling microscopy

M. Schmid, H. Stadler, and P. Varga

Institut für Allgemeine Physik, Technische Universität Wien, A-1040 Wien, Austria

Phys. Rev. Lett. 70 (1993) 1441-1444

We present the first scanning tunneling microscopy (STM) study which allows clear discrimination of two chemical species in a metal alloy. Special tunneling conditions, which we attribute to an adsorbate at the STM tip, cause a difference in corrugation between Pt and Ni atoms of 0.3 Å. The STM data reveal chemical short range order at the surface, which is in agreement with embedded atom simulations and can be understood as small domains of an L10 ordered phase.

Corresponding author: M. Schmid (schmid< encoded email address >).

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Part of this work is on display in the IAP/TU Wien STM Gallery (see the chemical resolution page).