FINE-STRUCTURE IN DIFFERENTIAL CONDUCTANCE OF OXIDIZED NICKEL OBSERVED IN A ROOM-TEMPERATURE STM EXPERIMENT

Direct measurements at room temperature of the current-voltage charact eristics I(V) of a junction between a scanning tunnelling microscope t ip made from W or Ni and an oxidized polycrystalline nickel surface ar e presented, with particular emphasis on a fine structure in the I(V) data. We show that it appears at voltages nearly corresponding to the energies of phonon and magnon excitations in tungsten, nickel and nick el oxide. We interpret the results obtained in terms of the mesoscopic dynamic processes that take place in tunnelling through specific atom ic-scale surface sites. (C) 1997 Elsevier Science Ltd. All rights rese rved.