Electronic and magnetic structure of the Cr(001) surface

Density functional theory (DFT) calculations are carried out to study the electronic and magnetic structure of the (001) surface of chromium. Our aim is to identify and characterize the most prominent electronic surface states and make the connection with the main experimental results. We show that a low dispersive minority spin surface state at the center of the surface Brillouin zone plays a crucial role. This surface state of Delta(1) symmetry at 0.58 eV above the Fermi level exhibits a predominantly d(z)2 as well as p(z) orbital character. Local density of states (LDOS) analysis in the vacuum above the surface shows that the sharp feature originating from this surface state persists far away above the surface because of the slow decay rate of the p(z) wavefunction. Finally, by artificially lowering the surface magnetic moment (m) over bar (S) on the outermost surface layer we find excellent agreement with experiments for (m) over bar (S) = 1.75 mu(B). In addition, we propose that some extra spin polarized scanning tunneling spectroscopy (SP-STS) experiments should be made at smaller tip-surface distances to reveal additional features originating from the majority spin d(z)2 surface state.