Author(s): A. Takayama, T. Sato, S. Souma, T. Oguchi, and T. Takahashi
To realize a one-dimensional (1D) system with strong spin-orbit coupling is a big challenge in modern physics, since the electrons in such a system are predicted to exhibit exotic properties unexpected from the 2D or 3D counterparts, while it was difficult to realize genuine physical properties inhe…
[Phys. Rev. Lett. 114, 066402] Published Mon Feb 09, 2015
Author(s): H. Oike, K. Miyagawa, H. Taniguchi, and K. Kanoda
We report the pressure study of a doped organic superconductor with a Hall coefficient and conductivity measurements. We find that maximally enhanced superconductivity and a marginal-Fermi liquid appear around a certain pressure where mobile carriers increase critically, suggesting a possible quantu...
[Phys. Rev. Lett. 114, 067002] Published Mon Feb 09, 2015
Dr.jens.bredeMikel?
Isotope Effects In their Communication on page 2052 ff., W. Ma, J. Zhao, and co-workers elucidated a proton-induced pathway for the TiO2-mediated photochemical dehalogenation of non-adsorbable aromatic bromides with an inverse kinetic solvent isotope effect.
Despite the numerous studies dedicated to phthalocyanine molecules adsorbed on surfaces, in monolayer or thin film, very few works have been focused on the characterization of vapors of these molecules. In this article we present the C 1s, N 1s and Fe 2p photoemission results as well as N K-edge X-ray absorption data of iron phthalocyanine (FePc) in gas phase. Presented comparison of X-ray photoelectron spectroscopy and X-ray absorption spectroscopy spectra of FePc films show a great similarity with the gas phase results, confirming the molecular character of thick films. The Fe 2p photoemission spectrum of the gas phase FePc, shown for the first time, can be considered as a fingerprint of the Fe(II) ionic state of the central metal of the iron phthalocyanine. The performed multiplet calculations for describing the Fe 2p XP spectrum indicate 
(a
e
b
) state as the most probable ground state for thick film of iron phthalocyanine.
Nature Nanotechnology 10, 156 (2015). doi:10.1038/nnano.2014.307
Authors: Yen-Chia Chen, Ting Cao, Chen Chen, Zahra Pedramrazi, Danny Haberer, Dimas G. de Oteyza, Felix R. Fischer, Steven G. Louie & Michael F. Crommie
Bandgap engineering is used to create semiconductor heterostructure devices that perform processes such as resonant tunnelling and solar energy conversion. However, the performance of such devices degrades as their size is reduced. Graphene-based molecular electronics has emerged as a candidate to enable high performance down to the single-molecule scale. Graphene nanoribbons, for example, can have widths of less than 2 nm and bandgaps that are tunable via their width and symmetry. It has been predicted that bandgap engineering within a single graphene nanoribbon may be achieved by varying the width of covalently bonded segments within the nanoribbon. Here, we demonstrate the bottom-up synthesis of such width-modulated armchair graphene nanoribbon heterostructures, obtained by fusing segments made from two different molecular building blocks. We study these heterojunctions at subnanometre length scales with scanning tunnelling microscopy and spectroscopy, and identify their spatially modulated electronic structure, demonstrating molecular-scale bandgap engineering, including type I heterojunction behaviour. First-principles calculations support these findings and provide insight into the microscopic electronic structure of bandgap-engineered graphene nanoribbon heterojunctions.
Nature Nanotechnology 10, 111 (2015). doi:10.1038/nnano.2014.337
Authors: Elio Mattia & Sijbren Otto
Article
The development of magnetism in metallic atomic chains is a widely debated phenomenon, of relevance to atomic-scale spintronics. Here, Strigl et al . measure the magneto-conductance of platinum break junctions stretched over sub-atomic distances, evidencing the evolution of distinct magnetic order.
Nature Communications doi: 10.1038/ncomms7172
Authors: Florian Strigl, Christopher Espy, Maximilian Bückle, Elke Scheer, Torsten Pietsch
Dr.jens.bredeDr. K? Thoughts? At least the spectra look better/different now...
Author(s): Michael Schackert, Tobias Märkl, Jasmin Jandke, Martin Hölzer, Sergey Ostanin, Eberhard K. U. Gross, Arthur Ernst, and Wulf Wulfhekel
Inelastic tunneling spectroscopy of Pb islands on Cu(111) obtained by scanning tunneling microscopy below 1 K provides a direct access to the local Eliashberg function of the islands with high energy resolution. The Eliashberg function describes the electron-phonon interaction causing conventional s...
[Phys. Rev. Lett. 114, 047002] Published Thu Jan 29, 2015
A key step in cytochrome P450 catalysis includes the spin-state crossing from low spin to high spin upon substrate binding and subsequent reduction of the heme. Clearly, a weak perturbation in P450 enzymes triggers a spin-state crossing. However, the origin of the process whereby enzymes reorganize their active site through external perturbations, such as hydrogen bonding, is still poorly understood. We have thus studied the impact of hydrogen-bonding interactions on the electronic structure of a five-coordinate iron(III) octaethyltetraarylporphyrin chloride. The spin state of the metal was found to switch reversibly between high (S=5/2) and intermediate spin (S=3/2) with hydrogen bonding. Our study highlights the possible effects and importance of hydrogen-bonding interactions in heme proteins. This is the first example of a synthetic iron(III) complex that can reversibly change its spin state between a high and an intermediate state through weak external perturbations.
Spin control: The electronic structure of a five-coordinate iron(III) porphinato chloride has been found to depend on the presence of hydrogen-bonding interactions, with the iron center switching reversibly between a high (S=5/2) and intermediate spin (S=3/2) state. Computational calculations clearly support the experimentally assigned spin state.
Nature Materials. doi:10.1038/nmat4205
Authors: F. Withers, O. Del Pozo-Zamudio, A. Mishchenko, A. P. Rooney, A. Gholinia, K. Watanabe, T. Taniguchi, S. J. Haigh, A. K. Geim, A. I. Tartakovskii & K. S. Novoselov
The advent of graphene and related 2D materials has recently led to a new technology: heterostructures based on these atomically thin crystals. The paradigm proved itself extremely versatile and led to rapid demonstration of tunnelling diodes with negative differential resistance, tunnelling transistors, photovoltaic devices and so on. Here, we take the complexity and functionality of such van der Waals heterostructures to the next level by introducing quantum wells (QWs) engineered with one atomic plane precision. We describe light-emitting diodes (LEDs) made by stacking metallic graphene, insulating hexagonal boron nitride and various semiconducting monolayers into complex but carefully designed sequences. Our first devices already exhibit an extrinsic quantum efficiency of nearly 10% and the emission can be tuned over a wide range of frequencies by appropriately choosing and combining 2D semiconductors (monolayers of transition metal dichalcogenides). By preparing the heterostructures on elastic and transparent substrates, we show that they can also provide the basis for flexible and semi-transparent electronics. The range of functionalities for the demonstrated heterostructures is expected to grow further on increasing the number of available 2D crystals and improving their electronic quality.
A comprehensive study of a force detected single-spin magnetic resonance measurement concept with atomic spatial resolution is presented. The method is based upon electrostatic force detection of spin-selection rule controlled single-electron tunneling between two electrically isolated paramagnetic states. Single spin magnetic resonance detection is possible by measuring the force detected tunneling charge noise on and off spin resonance. Simulation results of this charge noise, based upon physical models of the tunneling and spin physics, are directly compared to measured AFM system noise. The results show that the approach could provide single spin measurement of electrically isolated qubit states with atomic spatial resolution at room temperature.
Nature Physics. doi:10.1038/nphys3234
Authors: Felix Büttner, C. Moutafis, M. Schneider, B. Krüger, C. M. Günther, J. Geilhufe, C. v. Korff Schmising, J. Mohanty, B. Pfau, S. Schaffert, A. Bisig, M. Foerster, T. Schulz, C. A. F. Vaz, J. H. Franken, H. J. M. Swagten, M. Kläui & S. Eisebitt
Skyrmions are topologically protected winding vector fields characterized by a spherical topology. Magnetic skyrmions can arise as the result of the interplay of various interactions, including exchange, dipolar and anisotropy energy in the case of magnetic bubbles and an additional Dzyaloshinskii–Moriya interaction in the case of chiral skyrmions. Whereas the static and low-frequency dynamics of skyrmions are already well under control, their gigahertz dynamical behaviour has not been directly observed in real space. Here, we image the gigahertz gyrotropic eigenmode dynamics of a single magnetic bubble and use its trajectory to experimentally confirm its skyrmion topology. The particular trajectory points to the presence of strong inertia, with a mass much larger than predicted by existing theories. This mass is endowed by the topological confinement of the skyrmion and the energy associated with its size change. It is thereby expected to be found in all skyrmionic structures in magnetic systems and beyond. Our experiments demonstrate that the mass term plays a key role in describing skyrmion dynamics.
Nature Physics. doi:10.1038/nphys3186
Authors: S. Sahling, G. Remenyi, C. Paulsen, P. Monceau, V. Saligrama, C. Marin, A. Revcolevschi, L. P. Regnault, S. Raymond & J. E. Lorenzo
Author(s): Toma Susi, Duncan J. Mowbray, Mathias P. Ljungberg, and Paola Ayala
X-ray photoelectron spectroscopy combined with first-principles modeling is a powerful tool for determining the chemical composition and electronic structure of novel materials. Of these, graphene is an especially important model system for understanding the properties of other carbon nanomaterials....
[Phys. Rev. B 91, 081401] Published Mon Feb 02, 2015
Author(s): Matteo Michiardi, Marco Bianchi, Maciej Dendzik, Jill A. Miwa, Moritz Hoesch, Timur K. Kim, Peter Matzen, Jianli Mi, Martin Bremholm, Bo Brummerstedt Iversen, and Philip Hofmann
Near-surface two-dimensional electron gases on the topological insulator Bi2Te2Se are induced by electron doping and studied by angle-resolved photoemission spectroscopy. A pronounced spin-orbit splitting is observed for these states. The k-dependent splitting is strongly anisotropic to a degree whe...
[Phys. Rev. B 91, 035445] Published Fri Jan 30, 2015
Author(s): Weihua Wang, Rui Pang, Guowen Kuang, Xingqiang Shi, Xuesong Shang, Pei Nian Liu, and Nian Lin
Using cryogenic scanning tunneling microscopy, we measured the electronic states and Kondo resonance of single Fe(II)-porphyrin molecules adsorbed on a Au(111) surface with intramolecular resolution. We found that the Fe(II) ion introduces a spin-polarized molecular state near the Fermi level. Tunne...
[Phys. Rev. B 91, 045440] Published Fri Jan 30, 2015
Author(s): Jill A. Miwa, Søren Ulstrup, Signe G. Sørensen, Maciej Dendzik, Antonija Grubišić Čabo, Marco Bianchi, Jeppe Vang Lauritsen, and Philip Hofmann
The electronic structure of epitaxial single-layer MoS2 on Au(111) is investigated by angle-resolved photoemission spectroscopy. Pristine and potassium-doped layers are studied in order to gain access to the conduction band. The potassium-doped layer is found to have a (1.39±0.05) eV direct band ga...
[Phys. Rev. Lett. 114, 046802] Published Thu Jan 29, 2015
Article
When the insulators SrTiO3 and LaAlO3 are brought together, a two-dimensional electron gas forms that exhibits both superconductivity and magnetic behaviour. Mathias Scheurer and Jörg Schmalian propose a link between the topological nature of the superconducting state and its microscopic mechanism.
Nature Communications doi: 10.1038/ncomms7005
Authors: Mathias S Scheurer, Jörg Schmalian
Dr.jens.bredeDidn't even cite us....
Graphene, a two-dimensional (2D) material with unique electronic properties, appears to be an ideal object for the application of surface-science methods. Among them, a family of scanning probe microscopy methods (STM, AFM, KPFM) and the corresponding spectroscopy add-ons provide information about the structure and electronic properties of graphene on the local scale (from 
m to atoms). This review focuses on the recent applications of these microscopic/spectroscopic methods for the investigation of graphene on metals (interfaces, intercalation-like systems, graphene nanoribbons, and quantum dots, etc.). It is shown that very important information about interaction strength at the graphene/metal interfaces as well as about modification of the electronic spectrum of graphene at the Fermi level can be obtained on the local scale. The combination of these results with those obtained by other methods and comparison with recent theoretical data demonstrate the power of this approach for the investigation of the graphene-based systems.
STM image of a graphene island (quantum dot) on Ir(111).
Scanning probe microscopy and spectroscopy provide a unique opportunity to obtain information about the structure and electronic properties of graphene at the nanoscale. This Feature Article presents the recent most important findings on the electronic properties of graphene nanostructures on metals obtained by scanning tunnelling and atomic force microscopies and spectroscopies.
Dr.jens.bredeFigure 6c is so beautiful. :)
Maciej, can you send me the review?
Nature Chemistry 7, 105 (2015). doi:10.1038/nchem.2159
Authors: Willi Auwärter, David Écija, Florian Klappenberger & Johannes V. Barth
Bringing porphyrins in contact with well-defined interfaces generates a rich playground of chemical behaviour and properties for exploration and exploitation. This Review examines our current understanding of surface-confined tetrapyrroles and their embedding in nanoarchitectures - discussing both the structural and functional attributes, and methods by which to manipulate their intramolecular and organizational features.
Author(s): Ming-Hao Liu (劉明豪), Peter Rickhaus, Péter Makk, Endre Tóvári, Romain Maurand, Fedor Tkatschenko, Markus Weiss, Christian Schönenberger, and Klaus Richter
Artificial graphene consisting of honeycomb lattices other than the atomic layer of carbon has been shown to exhibit electronic properties similar to real graphene. Here, we reverse the argument to show that transport properties of real graphene can be captured by simulations using “theoretical arti...
[Phys. Rev. Lett. 114, 036601] Published Thu Jan 22, 2015