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The spin, in-plane and out-of-plane orbital and magnetic dipole moments of almost purely interfacial Co atoms were directly determined for Au/2-monolayer Co nanoclusters/Au(111) by angle-dependent magnetic circular x-ray dichroism (MCXD) measurements. The field- and temperature-dependent MCXD evidences a ferromagnetic(FM)-to-superparamagnetic phase transition in single-domain clusters with decreasing size. The interfacial moments are remarkably enhanced as compared with bulk values, verifying theoretical predictions. The FM clusters show strong perpendicular magnetic anisotropy, providing promise of applications for nanoscale magnetic bits.

The first observation of a magnetic circular x-ray dichroism (MCXD) at the Mn L2,3 core edges in antiferromagnetic LaMnO3 shows canted spin and orbital ( m(orb)) moments arising from lattice distortions. An L2,3-edge MCXD in ferromagnetic metals and insulators, La1-xSr(x)MnO3+delta, reveals that m(orb) of Mn strongly depends on x in the metallic regime but remains unchanged with the metal-to-insulator transition (x approximately 0.16). An O K-edge MCXD, which shows m(orb) of O caused by 2p-3d hybridization, is much larger in the ferromagnetic metal than insulator phases, sharply contrasting with m(orb) of Mn. Our findings indicate a close magnetism-lattice-hybridization coupling.