The bimetallic molecular compound Dimolybdenum tetraacetate (MoMo‐Methyl) is grown on a Cu(111) surface with submonolayer coverage. Scanning tunneling microscopy experiments reveal that the compound forms two different structural phases on the Cu surface, whose ratio can be reversibly controlled by changing the sample temperature. The so‐called chain‐phase is characterized by tilted MoMo dimers bonded to the Cu surface via the methyl groups. In the so‐called mesh‐phase, on the other hand, the molecules adsorb in a flat lying adsorption configuration with one of the Mo‐atoms in direct contact with the Cu surface. Crucially, the different structural properties of the two phases reflect the different inter‐ and intramolecular interactions between the Mo metal centers, as well as the different interactions between Mo and the Cu surface atoms. In this way, the structural changes result in a modification of the cooperative effects in the system. Therefore, it is proposed that the observed reversible structural phase transition could be used to control the strength of cooperative effects in MoMo‐Methyl on Cu(111).
We demonstrate the successful preparation of ordered C 60 films on Co/Au(111) by scanning tunneling microscopy (STM). In particular, we show that the C 60 molecules arrange in a close-packed hexagonal pattern after postdeposition annealing at T = 350 °C. From STM measurements with intramolecular resolution we find domains with different orientational ordering, that is ultimately a result of the lateral arrangement of the C 60 molecules on the Co surface. The local ordering of the various domains is also clearly reflected in the measured differential conductance spectra. In particular, we find an energetic shift of the LUMO + 1 due to the reconstruction of the cobalt substrate. Our study opens the way for the introduction of ordered "spinterfaces" in molecular spintronics.
The discovery and realization of graphene as an ideal two-dimensional (2D) material has triggered extensive efforts to create similar 2D materials with exciting spin-dependent properties. Here, we report on a novel Sn 2D superstructure on Au(111) that shows similarities and differences to the expected electronic features of ideal stanene. Using spin-and angle-resolved photoemission spectroscopy, we find that a particular Sn/Au superstructure reveals a linearly dispersing band centered at the Γ-point and below the Fermi level with antiparallel spin polarization and a Fermi velocity of v F ≈ 1×10 6 m/s, the same value as for graphene. We attribute the origin of the band structure to the hybridization between the Sn and the Au orbitals at the 2D Sn-Au interface. Considering that free-standing stanene simply cannot exist, our investigated structure is an important step towards the search of useful stanene-like overstructures for future technological applications.
We have investigated the atomic and electronic structure of the !√3 × √3% 30° SnAu2/Au(111) surface alloy. Low energy electron diffraction and scanning tunneling microscopy measurements show that the native herringbone reconstruction of bare Au (111) surface remains intact after formation of a long range ordered !√3 × √3% 30° SnAu2/Au(111) surface alloy. Angle-resolved photoemission and two-photon photoemission spectroscopy techniques reveal Rashba-type spin-split bands in the occupied valence band with comparable momentum space splitting as observed for the Au(111) surface state, but with a hole-like parabolic dispersion. Our experimental findings are compared with density functional theory (DFT) calculation that fully support our experimental findings. Taking advantage of the good agreement between our DFT calculations and the experimental results, we are able to extract that the occupied Sn-Au hybrid band is of (s, d)-orbital character while the unoccupied Sn-Au hybrid bands are of (p, d)-orbital character. Hence, we can conclude that the Rashba-type spin splitting of the hole-like Sn-Au hybrid surface state is caused by the significant mixing of Au dto Sn s-states in conjunction with the strong atomic spin-orbit coupling of Au, i.e., of the substrate.
Ferromagnetic thin films play a fundamental role in spintronic applications as a source for spin polarized carriers and in fundamental studies as ferromagnetic substrates. However, it is challenging to produce such metallic films with high structural quality and chemical purity on single crystalline substrates since the diffusion barrier across the metal-metal interface is usually smaller than the thermal activation energy necessary for smooth surface morphologies. Here, we introduce epitaxial thin Co films grown on an Au(111) single crystal surface as a thermally stable ferromagnetic thin film. Our structural investigations reveal an identical growth of thin Co/Au(111) films compared to Co bulk single crystals with large monoatomic Co terraces with an average width of 500 Å, formed after thermal annealing at 575 K. Combining our results from photoemission and Auger electron spectroscopy, we provide evidence that no significant diffusion of Au into the near surface region of the Co film takes place for this temperature and that no Au capping layer is formed on top of Co films. Furthermore, we show that the electronic valence band is dominated by a strong spectral contribution from a Co 3d band and a Co derived surface resonance in the minority band. Both states lead to an overall negative spin polarization at the Fermi energy.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.