Observations were made of the charge ordering of Fe ions in a magnetite (Fe3O4) (001) film surface using scanning tunnelling microscopy and spectroscopy with a non-magnetic W tip. The Fe3O4(001) film surface exhibited a B-plane termination with a (√2 x √2)R45° reconstruction. Fe cation rows running along the [110] direction exhibited a wave-like structure. The (√2 x √2)R45° surface reconstruction originated from the wave-like Fe rows. The current imaging tunnelling spectroscopy image exhibited the alternation of 2 different kinds of current peak, with a separation of about 0.6nm. Each current peak arose from the same local density of states of two Fe ions. The presence of Fe dimers with two different kinds of local density of states provides evidence for the charge ordering of Fe ions with different charge states. Scanning tunnelling microscopy and spectroscopy using a non-magnetic W tip permitted correlation of the charge ordering pattern with the surface structure.

Correlation between Surface Structure and Charge Ordering in Magnetite(001) Studied by Scanning Tunnelling Microscopy and Spectroscopy. A.Subagyo, K.Sueoka: Journal of Physics - Conference Series, 2007, 61, 1102-6