Quantum transport properties in atom-sized bridges of magnetic materials

摘要

When the tip of a scanning tunneling microscope (STM) is brought into contact with a metal surface and then lifted up, the contact remains as long as the tip is lifted less than about a few nanometers from the surface, and the atom-sized bridge is formed between the STM-tip and the metal surface. Its cross section consists of a few atoms to a few tens of atoms. Conductance of the bridge is measured as a function of the stretching length of the bridge, while the tip is lifted up. A stepwise variation of the conductance is experimentally observed roughly in units of 2e~2/h[1]. In previous papers, we have investigated the effects of the electron-electron scattering on the quantum transport phenomena in the atom-sized bridge for the half-filled and non-magnetic case with the aid of the Hubbard model [2,3]. In this paper, we pay attention to magetic state changes while stretching the bridge for the case away from the half-filled case (low electron density). And we investigate the effects of the magnetic properties on the quantum transport phenomena in the atomsized bridge [4].