Graphene exhibits unconventional two-dimensional electronic properties resulting from the symmetry of its quasiparticles, which leads to the concepts of pseudospin and electronic chirality. Here, we report that scanning tunneling microscopy can be used to probe these unique symmetry properties at the nanometer scale. They are reflected in the quantum interference pattern resulting from elastic scattering off impurities, and they can be directly read from its fast Fourier transform. Our data, complemented by theoretical calculations, demonstrate that the pseudospin and the electronic chirality in epitaxial graphene on SiC(0001) correspond to the ones predicted for ideal graphene.

The electronic structure of isolated bis(phthalocyaninato) terbium(III) molecules, a novel single-molecular-magnet (SMM), supported on the Cu(111) surface has been characterized by density functional theory and scanning tunneling spectroscopy. These studies reveal that the interaction with the metal surface preserves both the molecular structure and the large spin magnetic moment of the metal center. The 4f electron states are not perturbed by the adsorption while a strong molecular/metal interaction can induce the suppression of the minor spin contribution delocalized over the molecular ligands. The calculations show that the inherent spin magnetic moment of the molecule is only weakly affected by the interaction with the surface and suggest that the SMM character might be preserved.The miniaturization of information storage devices drives the search for new nanoscale magnetic materials. Single molecular magnets (SMMs) formed by metal-organic complexes are very promising candidates as their large spin ground-state and large magnetic anisotropy are characteristics of each isolated molecule.1 Moreover, these systems provide a natural playground to explore magnetism at the nanoscale. Their future technological applications, such as quantum computing and high-density magnetic storage devices, are presently hampered by the difficulty of adsorbing SMMs onto surfaces and, quite importantly, by the lack of understanding on whether their magnetic properties are modified upon adsorption. In particular, the nonapplicability of conventional techniques, which allow an in-vacuum deposition, has so far hindered the systematic study of individual molecular magnets on surfaces. Solution-based deposition techniques including drop casting, 2,3 Langmuir-Blodgett, 4 microcontact printing, 5 covalent Au-S attaching, 6 and surface functionalization 7 have been successfully used to transfer molecules to surfaces but the magnetic properties of the adsorbed molecules have so far not been demonstrated. 3 This has tentatively been assigned to an induced local disorder caused by the used deposition techniques or by the coupling to the surface. 8 In this letter, we describe the structural, magnetic and electronic properties of a surface-supported SMM by combining scanning tunneling microscopy (STM) and spectroscopy (STS) with numerical simulations based on density functional theory (DFT). Topographic images and conductance maps of isolated SMM (namely bis(phthalocyaninato) terbium(III)) achieved at several energies confirm that the molecular structure is unchanged by the interaction with the surface. The Tb-4f electron states, which are responsible for the large magnetic moment of the molecular magnet, are little affected by molecular adsorption on the metal surface. Thus, it can be expected that the SMM character of the surface supported bis(phthalocyaninato) terbium(III) (abbreviated by TbPc2) molecules is preserved.TbPc2 molecules represent the first example of mononuclear metal complexes behaving as SMMs (i.e., showing large mag...

Based on the experimental observation, that only the close vicinity of a magnetic impurity at metal surfaces determines its Kondo behaviour, we introduce a simple model which explains the Kondo temperatures observed for cobalt adatoms at the (111) and (100) surfaces of Cu, Ag, and Au. Excellent agreement between the model and scanning tunneling spectroscopy (STS) experiments is demonstrated. The Kondo temperature is shown to depend on the occupation of the d-level determined by the hybridization between adatom and substrate with a minimum around single occupancy.PACS numbers: 72.10. Fk, 72.15.Qm, 68.37.Ef Understanding the physics of a single spin supported on a metal host is at the basis of a bottom up approach to the design of high density magnetic recording [1]. The effects occuring in the limit of very small magnetic structures can be studied macroscopically on dilute magnetic alloys or microscopically for single magnetic impurities [2,3] and spins in quantum dots [4,5]. These systems develop a rich phenomenology -which is commonly referred to as the Kondo problem [6]. It deals with the interaction of a magnetic impurity with the conduction electrons of a surrounding non-magnetic metal host. This interaction leads to the screening of the spin of the impurity and in consequence to anomalies in the macroscopic properties. A many body ground state is formed at temperatures well below the Kondo temperature T K . Once the Kondo temperature of a given system is known, its behaviour at low temperatures is completely determined. The first experimental evidence became available 70 years ago by measurements of the resistivity of nonmagnetic metals with minute amounts of magnetic impurities [7] which showed an anomalous behaviour below T K . It is only recently, that interest has revived through the investigation of Kondo phenomena in quantum dots on one hand -providing model systems, which allow tuning of the relevant Kondo parameters easily [4,5], and of single magnetic impurities using low temperature scanning tunneling microscopy (STM) and spectroscopy (STS) on the other hand. The spectroscopic signature of the Kondo effect,