A study on dual-tip scanning tunneling microscopy and nanoscale surface material science

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The aim of this work was to establish a basis for the study of the nanoscale functional surface materials. To this end, we have studied (1) the basic operation principle of dual-tip scanning tunneling microscopy for the study of transportand dynamical properties of nanoscale surface materials, and (2) the novel surface materials which undergo charge-density-wave phase transitions.As to the dual-tip scanning tunneling microscopy, we first studied the thermal-drift characteristics of an ultrahigh vacuum high-resolution scanning tunneling microscopy and developped a system for the fast measurement of the scanning tunneling spectroscopy. In order to establish the stable operation of the dual-tip scanning tunneling microscopy with two tips positioned in close proximity, we have studied several operation algorisms for the stabilization of distance between two tips.The atomic and electronic structure of In monolayers on Cu(001) was studied by means of scanning tunneling microscopy, angle-resolved photoelectron spectroscopy, and low-energy electron diffraction. We have found that two reversible phase transitions observed in this system are essentially the charge-density-wave transitions due to the nesting of the Fermi surface constituted by the In-induced surface resonance bands. It is expected that the surface electronic conductivity exhibits a strong change Hpon the phase transition. We also studied the structure of several related systems and found that Bi atoms form one-dimensionally-alligned zigzag chains on Ag(001), which would serve a new example of quasi-one-dimensional conductor.