Atomic-scale visualization of the p-d hybridization in III-V semiconductor surfaces doped with transition metal impurities

The p-d hybridization of transition metal impurities in a semiconductor host is the mechanism that couples valence-band electrons and localized spins. We use scanning tunneling microscopy and spectroscopy combined with density functional theory to probe at the atomic-scale hybridization of Cr single impurities with a GaAs host. Combining spatial density of states mapping and in-gap state spectroscopy of the Cr substituted at the surface of the semiconductor, we give a detailed picture of the spatial extension and the electronic structure of the strongly anisotropic wave function of Cr on GaAs(110). First-principles calculations allow us to identify the electronic character and origin of each state and show that the main resonance peaks and the wave function with ???drop-eye??? lobes experimentally observed for 3d metal impurities in III-V semiconductors are direct local evidences of p-d hybridization.