TUNNELING SPECTROSCOPY OF BCC(001) SURFACE-STATES

We have discovered an intense, sharp feature in tunneling spectra of t he Fe(001) and Cr(001) surfaces that derives from a bce surface state near the Fermi level. Band-structure calculations show that this state is a general feature of bcc (001) surfaces, and that it originates fr om a nearly unperturbed d orbital extending out into the vacuum region . This general feature should permit chemical identification with atom ic spatial resolution on bcc (001) surfaces. The surface state is in t he minority spin band for Fe and Cr, so it should be useful for future spin-polarized tunneling experiments.