Scattering of surface-state electrons by the monatomic step in Fe(001): Differential conductivity imaging by scanning tunneling microscopy

The influence of steps on the surface states of the magnetic Fe(001) surface was studied at room temperature by scanning tunneling microscopy (STM). We observed the distinct bias-dependent differential conductivity (dI/dV) contrasts at step edges from those on flat terraces. The observed dI/dV line profiles across the step edge exhibit the strong reduction of the empty-state local density of states up to 1 eV above the Fermi level. That can be attributed to the scattering of the minority-spin surface states by the step edge, thus, a sizable spin-dependent contrast at the step edge is predicted in spin-polarized STM.