Quantized conductance in an atom-size bridge made from magnetic materials

With the aid of the Hubbard model, and considering orbital degeneracies, we investigate how the magnetic properties of atom-size bridges affect the qu antum transport of electrons through them. Within the Hartree-Fock approxim ation, we calculate the corresponding total energy of the electron system o f the atom-size bridge as it is stretched in length. Our numerical results show that stretching the atom-size bridge induces changes in its magnetic s tate, from paramagnetic to ferromagnetic, and also vice versa. Furthermore, the corresponding conductance variation of the atom-size bridge is demonst rated. (C) 2000 American Institute of Physics. [S0021-8979(00)09617-1].