SCANNING-TUNNELING-MICROSCOPY AND SPECTROSCOPY ON THIN FE3O4 (110) FILMS ON MGO

Thin Fe3O4 (110) films, grown by molecular-beam epitaxy on MgO, have b een studied by scanning tunneling microscopy and spectroscopy. A 500-A ngstrom-thick film was cleaned prior to the measurements by annealing at 850 K under ultrahigh vacuum. Tunneling images show the onset of th e formation of the one-dimensional row reconstruction, which was previ ously also observed on surfaces of bulk single crystals cleaned by ion bombardment and subsequent annealing. Spectroscopic current-voltage c urves reveal different behavior depending on the location of the tip a bove the row reconstruction. Most notably, when probing the filled sta tes at negative sample bias, a larger current was found on top of the rows as compared to a tip position between two rows. (C) 1996 American Vacuum Society.