Electronic structure of the Cr(001) surface and Cr/MgO interface

We have undertaken a detailed study of the Cr surface and Cr/MgO interface electronic properties by symmetryand angle- resolved photoemission spectroscopy on a Cr(001) surface covered or not with 1.2 monolayer MgO. For the bare Cr(001) film, the experimental bulk dispersions are in good agreement with the theoretical band structure, and characteristic antiferromagnetic features like the antiferromagnetic gap at the X point are observed. However, by covering the Cr film by 1.2 monolayer MgO, the observed experimental dispersions are strongly perturbed as a result of the existence of metal- induced gap states in the MgO film. By carrying out normal emission measurements, we detect two 2D localized states for the Cr(001) surface that persist at the Cr/MgO interface: a Delta 1 state at very low binding energy, which is usually associated with Cr surface magnetism, and an additional resonant Delta 5 state, which shall play a crucial role for transport and coupling in Cr/MgO epitaxial systems.