Dr.jens.brede

Nature Chemistry 8, 220 (2016). doi:10.1038/nchem.2438

Authors: Bruno Schuler, Shadi Fatayer, Fabian Mohn, Nikolaj Moll, Niko Pavliček, Gerhard Meyer, Diego Peña & Leo Gross

The Bergman cyclization is a fascinating rearrangement reaction with implications beyond organic chemistry. It has now been shown that a reversible Bergman cyclization reaction in a single molecule sitting on an ultrathin NaCl film can be triggered and directly imaged using atomic force microscopy. The interconverted diradical and diyne products are shown to have distinct chemical and physical properties.

Abstract

Nature Materials. doi:10.1038/nmat4566

Authors: Shunsuke Fukami, Chaoliang Zhang, Samik DuttaGupta, Aleksandr Kurenkov & Hideo Ohno

Nanoscale control of charge doping in two-dimensional (2D) materials permits the realization of electronic analogs of optical phenomena, relativistic physics at low energies, and technologically promising nanoelectronics. Electrostatic gating and chemical doping are the two most common methods to achieve local control of such doping. However, these approaches suffer from complicated fabrication processes that introduce contamination, change material properties irreversibly, and lack flexible pattern control. Here we demonstrate a clean, simple, and reversible technique that permits writing, reading, and erasing of doping patterns for 2D materials at the nanometer scale. We accomplish this by employing a graphene/boron nitride (BN) heterostructure that is equipped with a bottom gate electrode. By using electron transport and scanning tunneling microscopy (STM), we demonstrate that spatial control of charge doping can be realized with the application of either light or STM tip voltage excitations in conjunction with a gate electric field. Our straightforward and novel technique provides a new path towards on-demand graphene pn junctions and ultra-thin memory devices.

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Does it take too long to publish research?

Nature 530, 7589 (2016). http://www.nature.com/doifinder/10.1038/530148a

Author: Kendall Powell

Scientists are becoming increasingly frustrated by the time it takes to publish a paper. Something has to change, they say.

Nature advance online publication 08 February 2016. doi:10.1038/nature16522

Authors: M. Mitrano, A. Cantaluppi, D. Nicoletti, S. Kaiser, A. Perucchi, S. Lupi, P. Di Pietro, D. Pontiroli, M. Riccò, S. R. Clark, D. Jaksch & A. Cavalleri

The non-equilibrium control of emergent phenomena in solids is an important research frontier, encompassing effects such as the optical enhancement of superconductivity. Nonlinear excitation of certain phonons in bilayer copper oxides was recently shown to induce superconducting-like optical properties at temperatures far greater than the superconducting transition temperature, Tc (refs 4, 5, 6). This effect was accompanied by the disruption of competing charge-density-wave correlations, which explained some but not all of the experimental results. Here we report a similar phenomenon in a very different compound, K3C60. By exciting metallic K3C60 with mid-infrared optical pulses, we induce a large increase in carrier mobility, accompanied by the opening of a gap in the optical conductivity. These same signatures are observed at equilibrium when cooling metallic K3C60 below Tc (20 kelvin). Although optical techniques alone cannot unequivocally identify non-equilibrium high-temperature superconductivity, we propose this as a possible explanation of our results.

Article

Two dimensional forms of silicon offer different conductive properties to that of the bulk material, promising applications in new electronic technologies. Here, the authors report the fabrication of bilayer silicenes which, unlike their monolayer form, are indirect bandgap semiconductors.

Nature Communications doi: 10.1038/ncomms10657

Authors: Ritsuko Yaokawa, Tetsu Ohsuna, Tetsuya Morishita, Yuichiro Hayasaka, Michelle J. S. Spencer, Hideyuki Nakano

Author: Rima Wilkes

Antiferromagnets are hard to control by external magnetic fields because of the alternating directions of magnetic moments on individual atoms and the resulting zero net magnetization. However, relativistic quantum mechanics allows for generating current-induced internal fields whose sign alternates with the periodicity of the antiferromagnetic lattice. Using these fields, which couple strongly to the antiferromagnetic order, we demonstrate room-temperature electrical switching between stable configurations in antiferromagnetic CuMnAs thin-film devices by applied current with magnitudes of order 106 ampere per square centimeter. Electrical writing is combined in our solid-state memory with electrical readout and the stored magnetic state is insensitive to and produces no external magnetic field perturbations, which illustrates the unique merits of antiferromagnets for spintronics. Authors: P. Wadley, B. Howells, J. Železný, C. Andrews, V. Hills, R. P. Campion, V. Novák, K. Olejník, F. Maccherozzi, S. S. Dhesi, S. Y. Martin, T. Wagner, J. Wunderlich, F. Freimuth, Y. Mokrousov, J. Kuneš, J. S. Chauhan, M. J. Grzybowski, A. W. Rushforth, K. W. Edmonds, B. L. Gallagher, T. Jungwirth

Author(s): S. Krause, A. Sonntag, J. Hermenau, J. Friedlein, and R. Wiesendanger

The magnetization dynamics of individual nanomagnets is studied by spin-polarized scanning tunneling microscopy, combining real-time telegraphic noise analysis with pump-probe schemes. A transition between two Arrhenius regimes is observed as a function of temperature. The switching rates at high te…

[Phys. Rev. B 93, 064407] Published Thu Feb 04, 2016

Article

Magnetic stability of holmium atoms on a platinum(111) surface has recently been reported, raising prospects for atomic-scale spintronics, however contradictory results have since emerged. Here, Steinbrecher et al. find evidence for an invisibility of the holmium spin to scanning tunnelling spectroscopy techniques which challenges recent results.

Nature Communications doi: 10.1038/ncomms10454

Authors: M. Steinbrecher, A. Sonntag, M. dos Santos Dias, M. Bouhassoune, S. Lounis, J. Wiebe, R. Wiesendanger, A. A. Khajetoorians

Nature Nanotechnology 11, 177 (2016). doi:10.1038/nnano.2015.245

Authors: Sanjukta Bhanja, D. K. Karunaratne, Ravi Panchumarthy, Srinath Rajaram & Sudeep Sarkar

Nature Nanotechnology 11, 112 (2016). doi:10.1038/nnano.2016.8

Author: Christian Martin

Work on a new technology roadmap and an exceptional wave of consolidation hint at fundamental changes in the micro- and nanoelectronics industry, as Christian Martin explains.

Abstract

Abstract

Author(s): Benedikt Schweflinghaus, Manuel dos Santos Dias, and Samir Lounis

Spin excitations in atomic-scale nanostructures have been investigated with inelastic scanning tunneling spectroscopy, sometimes with conflicting results. In this work, we present a theoretical viewpoint on a recent experimental controversy regarding the spin excitations of Co adatoms on Pt(111). Wh…

[Phys. Rev. B 93, 035451] Published Wed Jan 27, 2016

Article

Iron Fe 2+ ions embedded in semiconductor matrix usually have zero magnetic moment in the ground state. Here, the authors show theoretically and experimentally that a nearly doubly degenerate magnetic ground state is produced when iron ions are subjected to strain in epitaxial quantum dots, suggesting they could be used in spintronics and solotronics.

Nature Communications doi: 10.1038/ncomms10484

Authors: T. Smoleński, T. Kazimierczuk, J. Kobak, M. Goryca, A. Golnik, P. Kossacki, W. Pacuski