Spin moments, orbital moments and magnetic anisotropy of finite-length Co wires deposited on Pd(110)
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The ground-state spin moments 〈Sz〉, orbital moments 〈Lz〉 and magnetic anisotropy energy (MAE) of CoN one-dimensional (1D) clusters (N < 12) deposited on the Pd(110) surface are determined in the framework of a selfconsistent, real-space tight-binding method. Remarkably large total magnetic moments per Co atom, Mz = (2〈Sz〉 %2b 〈Lz〉)/N = 2.8-2.9 μB, are obtained, which can be understood as the result of three physically distinct effects. The first and leading contribution is given by the local spin moments 〈Siz〉 at the Co atoms i = 1,N (2〈Siz〉Co ≃ 1.6 μB). Second, significant spin moments are induced at the Pd atoms i > N close to the Co-Pd interface, which amount to about 25%25 of Mz (2〈Siz〉 Pd = 0.2-0.3 μB). Finally, enhanced orbital magnetic moments 〈Liz〉 are responsible for approximately 20%25 of Mz. In the case of the Co atoms, 〈Liz〉 Co = 0.28-0.33 μB is almost a factor of three larger than the Co bulk orbital moment, while in Pd atoms 〈Liz〉 Pd = 0.05 μB represents about 15%25 of the total local moment μiz = 2〈Siz〉 %2b 〈L iz〉. These results and the associated MAEs are analysed from a local perspective. The role of the cluster-surface interactions is discussed by comparison with the corresponding results for free-standing wires. Particularly in the case of monatomic 1D Co chains we observe that the lowest-energy magnetization direction (easy axis) changes from in line to off plane upon deposition on Pd(110). Wire-substrate hybridizations are therefore crucial for the magneto-anisotropic behaviour of 1D magnetic nanostructures on metallic substrates.
