We have studied the spin and exchange coupling of Ti atoms deposited on a Cu2N/Cu(100) surface using density functional theory with generalized gradient approximation +U. In agreement with experiments, we find that Ti has the highest binding on top of Cu atoms. We also find that the spin of individual Ti atoms deposited on the Cu2N/Cu(100) surface increases as Ti coverage on the surface is decreased. For U=0, the spin of a Ti atom starts at S=0 at high coverages and increases to S=1/2 as the coverage is decreased, which agrees very well with results obtained from STM experiments. At higher values of U, the spin of Ti is found to be close to 1 regardless of coverage. We also calculate the exchange coupling for Ti dimers on the Cu2N/Cu(100) surface and we find that the exchange coupling across a 'void' of 3.6Å is antiferromagnetic, whereas indirect (superexchange) coupling through a N atom is ferromagnetic. For a square lattice of Ti on Cu2N/Cu(100), we nd a novel spin striped phase.
Raghani, Pushpa; Cruz, Jesus; and Jones, Barbara. (2011). "Spin and Exchange Coupling for Ti Embedded in a Surface Dipolar Network". Physical Review B, 84(7), . http://dx.doi.org/10.1103/PhysRevB.84.075422