Study of Pt–Cu Nanocontact Formation Processes during the Indentation of a Scanning Tunneling Microscope Tip into a Pt/Cu Surface Alloy by Computer Simulations

The formation of nanocontacts during the indentation of a scanning tunneling microscope (STM) tip into a Pt/Cu surface alloy has been studied by the molecular dynamics method. It has been established that the Pt atoms move in the copper nanocontact through jumps over atomic layers in the direction from the copper surface to the base of the STM tip, while the Cu atoms move in the opposite direction. The formation of nanocontacts for various orientations of the STM tip, a temperature from 300 to 800 K, and various numbers of Pt atoms immediately beneath the STM tip has been studied. It is shown that the probability of the formation of a mixed Pt–Cu nanocontact can reach 50%.