ABSTRACT: We have analyzed spin quenching of first row transition metals
deposited on (001) defect-free and defect-containing surfaces of MgO insulator and CdO
semiconductor by means of density functional calculations and embedded cluster
model. Clusters of moderate sizes were embedded in the simulated Coulomb fields that
closely approximate the Madelung fields of the host surfaces, and relaxation of ions that
surround the defect sites was taken into account. Spin states of metals deposited on the
defect free surfaces were maintained as in the isolated metals except for Ti, V, and Co
on MgO, and Ti, V, and Cr on CdO. On the defect containing surfaces, spin states were
maintained too except for Fe on MgO, and V and Cr on CdO. The metal-support
interactions stabilize the low spin state of the adsorbed metal with respect to the
isolated metal, but the effect was not in general enough to quench the spin. Spin
polarization effects tend to preserve the spin states of the adsorbed metals relative to
those of the isolated metals. Although charge transfer took place from the adsorbed
metal to the insulator surface, it took place the other way round from the
semiconductor surface to the adsorbed metal. The encountered variations in magnetic
properties were attributed to the smaller band gap of the semiconductor, and the
behavior of a single metal atom adsorbed on a particular surface was a result of a
competition between Hund’s rule for the adsorbed metal and the formation of a
chemical bond at the interface. VC 2010 Wiley Periodicals, Inc. Int J Quantum Chem |
