Clean (100) surfaces of a synthetic single crystal of magnetite (Fe3O4) hav
e been prepared in situ using current pulses in a scanning tunneling micros
cope without subsequent annealing. We have observed atomically resolved ter
races with rows of Fe2+ and Fe3+ ions of the B-sublattice: (octahedrally co
ordinated lattice sites). Along these rows a long-distance corrugation (sim
ilar to 12W) has been observed at 300K using in situ prepared Fe tunneling
tips. This corrugation is interpreted as a Wigner localization associated w
ith a Verwey transition above 300K in the top surface layer.