Scanning Tunneling Microscopy Studies of Fe on GaAs (110) Surface

The introduction of transition metal impurities into semiconductors allows for the study of magnetic phenomena in a multifunctional host material. Using scanning tunneling microscopy (STM) to study individual magnetic dopants allows for magnetic interactions to be probed on an atomic scale. Here we investigate the interaction of Fe adatoms with a host GaAs (110) surface using STM. A GaAs wafer was cleaved in situ at cryogenic temperatures to reveal a pristine (110) surface. Electron beam evaporation was used to deposit iron adatoms onto the GaAs (110) surface. Upon deposition, the Fe atoms replaced Ga atoms on the surface. STM was used to image the substituted Fe atoms in empty and filled electronic states and to probe the local density of states (LDOS) via differential conductance spectroscopy. The substituted iron show a range of topographic contrast, which is also reflected in the associated differential conductance spectroscopy. This contrast may reflect distinct charge/spin states. In addition, we present topographic images and differential conductance spectroscopy of Fe dimers as a function of spatial separation. We highlight the variations in spectroscopy as the separation distance between the iron atoms in the dimers change.