Unoccupied states of Cr on Au(100), Ag(100), and Cu(100).

Abstract

Chromium is deposited epitaxially onto Au(100), Ag(100), and Cu(100), and the effect of the substrate lattice constant on the Cr 3d states is determined with inverse photoemission. A 1\ifmmode\times\else\texttimes\fi{}1, 1\ifmmode\times\else\texttimes\fi{}1, and 3\ifmmode\times\else\texttimes\fi{}1 registry is found, respectively. For a monolayer of Cr on Au(100) and Ag(100) we find peaks at 1.8 and 1.6 eV above the Fermi level, respectively, which is assigned to a ${\mathrm{\ensuremath{\Delta}}}_{5}$(${\mathit{d}}_{\mathit{x}\mathit{z},}$yz) state. Together with photoemission results this implies a magnetic splitting of 2.5--2.6 eV and 2.7 eV, respectively, which is consistent with theoretical predictions of enhanced monolayer magnetism. For a Cr monolayer on Cu(100) we observe a peak at 1.0 eV that lies between the two magnetically split states on Au(100) and Ag(100). This is consistent with a collapse of the magnetic splitting caused by the lateral compression of the Cr film on Cu(100) relative to Ag(100) and Au(100).