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Nature Materials

Ananth Govind Rajan, Kevin S Silmore, Jacob Swett, Alex W Robertson, Jamie H Warner, Daniel Blankschtein, Michael S Strano
The presence of extended defects or nanopores in two-dimensional (2D) materials can change the electronic, magnetic and barrier membrane properties of the materials. However, the large number of possible lattice isomers of nanopores makes their quantitative study a seemingly intractable problem, confounding the interpretation of experimental and simulated data. Here we formulate a solution to this isomer cataloguing problem (ICP), combining electronic-structure calculations, kinetic Monte Carlo simulations, and chemical graph theory, to generate a catalogue of unique, most-probable isomers of 2D lattice nanopores...
January 14, 2019: Nature Materials
Petr Král
No abstract text is available yet for this article.
January 14, 2019: Nature Materials
Björn Lüssem
No abstract text is available yet for this article.
January 14, 2019: Nature Materials
David Kiefer, Renee Kroon, Anna I Hofmann, Hengda Sun, Xianjie Liu, Alexander Giovannitti, Dominik Stegerer, Alexander Cano, Jonna Hynynen, Liyang Yu, Yadong Zhang, Dingqi Nai, Thomas F Harrelson, Michael Sommer, Adam J Moulé, Martijn Kemerink, Seth R Marder, Iain McCulloch, Mats Fahlman, Simone Fabiano, Christian Müller
Molecular doping is a crucial tool for controlling the charge-carrier concentration in organic semiconductors. Each dopant molecule is commonly thought to give rise to only one polaron, leading to a maximum of one donor:acceptor charge-transfer complex and hence an ionization efficiency of 100%. However, this theoretical limit is rarely achieved because of incomplete charge transfer and the presence of unreacted dopant. Here, we establish that common p-dopants can in fact accept two electrons per molecule from conjugated polymers with a low ionization energy...
January 14, 2019: Nature Materials
D Scott Wilson, Sachiko Hirosue, Michal M Raczy, Leonardo Bonilla-Ramirez, Laura Jeanbart, Ruyi Wang, Marcin Kwissa, Jean-Francois Franetich, Maria A S Broggi, Giacomo Diaceri, Xavier Quaglia-Thermes, Dominique Mazier, Melody A Swartz, Jeffrey A Hubbell
Fully effective vaccines for complex infections must elicit a diverse repertoire of antibodies (humoral immunity) and CD8+ T-cell responses (cellular immunity). Here, we present a synthetic glyco-adjuvant named p(Man-TLR7), which, when conjugated to antigens, elicits robust humoral and cellular immunity. p(Man-TLR7) is a random copolymer composed of monomers that either target dendritic cells (DCs) via mannose-binding receptors or activate DCs via Toll-like receptor 7 (TLR7). Protein antigens are conjugated to p(Man-TLR7) via a self-immolative linkage that releases chemically unmodified antigen after endocytosis, thus amplifying antigen presentation to T cells...
January 14, 2019: Nature Materials
Félix Thouin, David A Valverde-Chávez, Claudio Quarti, Daniele Cortecchia, Ilaria Bargigia, David Beljonne, Annamaria Petrozza, Carlos Silva, Ajay Ram Srimath Kandada
Hybrid organic-inorganic semiconductors feature complex lattice dynamics due to the ionic character of the crystal and the softness arising from non-covalent bonds between molecular moieties and the inorganic network. Here we establish that such dynamic structural complexity in a prototypical two-dimensional lead iodide perovskite gives rise to the coexistence of diverse excitonic resonances, each with a distinct degree of polaronic character. By means of high-resolution resonant impulsive stimulated Raman spectroscopy, we identify vibrational wavepacket dynamics that evolve along different configurational coordinates for distinct excitons and photocarriers...
January 14, 2019: Nature Materials
Young-Shin Park, Jaehoon Lim, Victor I Klimov
The application of colloidal semiconductor quantum dots as single-dot light sources still requires several challenges to be overcome. Recently, there has been considerable progress in suppressing intensity fluctuations (blinking) by encapsulating an emitting core in a thick protective shell. However, these nanostructures still show considerable fluctuations in both emission energy and linewidth. Here we demonstrate type-I core/shell heterostructures that overcome these deficiencies. They are made by combining wurtzite semiconductors with a large, directionally anisotropic lattice mismatch, which results in strong asymmetric compression of the emitting core...
January 7, 2019: Nature Materials
Zhengyou Liu
No abstract text is available yet for this article.
December 31, 2018: Nature Materials
Xiang Ni, Matthew Weiner, Andrea Alù, Alexander B Khanikaev
Topological systems are inherently robust to disorder and continuous perturbations, resulting in dissipation-free edge transport of electrons in quantum solids, or reflectionless guiding of photons and phonons in classical wave systems characterized by topological invariants. Recently, a new class of topological materials characterized by bulk polarization has been introduced, and was shown to host higher-order topological corner states. Here, we demonstrate theoretically and experimentally that 3D-printed two-dimensional acoustic meta-structures can possess nontrivial bulk topological polarization and host one-dimensional edge and Wannier-type second-order zero-dimensional corner states with unique acoustic properties...
December 31, 2018: Nature Materials
Haoran Xue, Yahui Yang, Fei Gao, Yidong Chong, Baile Zhang
Higher-order topological insulators1-5 are a family of recently predicted topological phases of matter that obey an extended topological bulk-boundary correspondence principle. For example, a two-dimensional (2D) second-order topological insulator does not exhibit gapless one-dimensional (1D) topological edge states, like a standard 2D topological insulator, but instead has topologically protected zero-dimensional (0D) corner states. The first prediction of a second-order topological insulator1 , based on quantized quadrupole polarization, was demonstrated in classical mechanical6 and electromagnetic7,8 metamaterials...
December 31, 2018: Nature Materials
Jed A Hartings
No abstract text is available yet for this article.
December 31, 2018: Nature Materials
Awadhesh Narayan, Andrés Cano, Alexander V Balatsky, Nicola A Spaldin
The zero-temperature limit of a continuous phase transition is marked by a quantum critical point, which can generate physical effects that extend to elevated temperatures. Magnetic quantum criticality is now well established, and has been explored in systems ranging from heavy fermion metals to quantum Ising materials. Ferroelectric quantum critical behaviour has also been recently demonstrated, motivating a flurry of research investigating its consequences. Here, we introduce the concept of multiferroic quantum criticality, in which both magnetic and ferroelectric quantum criticality occur in the same system...
December 31, 2018: Nature Materials
Eduard Masvidal-Codina, Xavi Illa, Miguel Dasilva, Andrea Bonaccini Calia, Tanja Dragojević, Ernesto E Vidal-Rosas, Elisabet Prats-Alfonso, Javier Martínez-Aguilar, Jose M De la Cruz, Ramon Garcia-Cortadella, Philippe Godignon, Gemma Rius, Alessandra Camassa, Elena Del Corro, Jessica Bousquet, Clement Hébert, Turgut Durduran, Rosa Villa, Maria V Sanchez-Vives, Jose A Garrido, Anton Guimerà-Brunet
Recording infraslow brain signals (<0.1 Hz) with microelectrodes is severely hampered by current microelectrode materials, primarily due to limitations resulting from voltage drift and high electrode impedance. Hence, most recording systems include high-pass filters that solve saturation issues but come hand in hand with loss of physiological and pathological information. In this work, we use flexible epicortical and intracortical arrays of graphene solution-gated field-effect transistors (gSGFETs) to map cortical spreading depression in rats and demonstrate that gSGFETs are able to record, with high fidelity, infraslow signals together with signals in the typical local field potential bandwidth...
December 31, 2018: Nature Materials
Bo Sun, Georg Haunschild, Carlos Polanco, James Zi-Jian Ju, Lucas Lindsay, Gregor Koblmüller, Yee Kan Koh
Dislocations, one-dimensional lattice imperfections, are common to technologically important materials such as III-V semiconductors, and adversely affect heat dissipation in, for example, nitride-based high-power electronic devices. For decades, conventional nonlinear elasticity models have predicted that this thermal resistance is only appreciable when the heat flux is perpendicular to the dislocations. However, this dislocation-induced anisotropic thermal transport has yet to be seen experimentally. Using time-domain thermoreflectance, we measure strong thermal transport anisotropy governed by highly oriented threading dislocation arrays throughout micrometre-thick, single-crystal indium nitride films...
December 17, 2018: Nature Materials
Masahiro Yoshida, Menaka De Zoysa, Kenji Ishizaki, Yoshinori Tanaka, Masato Kawasaki, Ranko Hatsuda, Bongshik Song, John Gelleta, Susumu Noda
Achieving high brightness (where brightness is defined as optical power per unit area per unit solid angle) in semiconductor lasers is important for various applications, including direct-laser processing and light detection and ranging for next-generation smart production and mobility. Although the brightness of semiconductor lasers has been increased by the use of edge-emitting-type resonators, their brightness is still one order of magnitude smaller than that of gas and solid-state/fibre lasers, and they often suffer from large beam divergence with strong asymmetry and astigmatism...
December 17, 2018: Nature Materials
He Zhao, Zheng Ren, Bryan Rachmilowitz, John Schneeloch, Ruidan Zhong, Genda Gu, Ziqiang Wang, Ilija Zeljkovic
High-temperature (high-Tc ) superconductivity in cuprates arises from carrier doping of an antiferromagnetic Mott insulator. This carrier doping leads to the formation of electronic liquid-crystal phases1 . The insulating charge-stripe crystal phase is predicted to form when a small density of holes is doped into the charge-transfer insulator state1-3 , but this phase is yet to be observed experimentally. Here, we use surface annealing to extend the accessible doping range in Bi-based cuprates and realize the lightly doped charge-transfer insulating state of the cuprate Bi2 Sr2 CaCu2 O8+x ...
December 17, 2018: Nature Materials
Xiaojian Zhu, Da Li, Xiaogan Liang, Wei D Lu
Coupled ionic-electronic effects present intriguing opportunities for device and circuit development. In particular, layered two-dimensional materials such as MoS2 offer highly anisotropic ionic transport properties, facilitating controlled ion migration and efficient ionic coupling among devices. Here, we report reversible modulation of MoS2 films that is consistent with local 2H-1T' phase transitions by controlling the migration of Li+ ions with an electric field, where an increase/decrease in the local Li+ ion concentration leads to the transition between the 2H (semiconductor) and 1T' (metal) phases...
December 17, 2018: Nature Materials
Gang Chen, Kyle J Gibson, Di Liu, Huw C Rees, Jung-Hoon Lee, Weiwei Xia, Ruoqian Lin, Huolin L Xin, Oleg Gang, Yossi Weizmann
In the version of this Article originally published, the diblock copolymer structure in Fig. 2a showed a single bond between the carbon and the oxygen atoms; it should have been a double bond. This has been corrected in all versions of the Article.
December 12, 2018: Nature Materials
Puritut Nakhanivej, Xu Yu, Sul Ki Park, Soo Kim, Jin-Yong Hong, Hae Jin Kim, Wonki Lee, Jun Yeon Hwang, Ji Eun Yang, Chris Wolverton, Jing Kong, Manish Chhowalla, Ho Seok Park
Bulk and two-dimensional black phosphorus are considered to be promising battery materials due to their high theoretical capacities of 2,600 mAh g-1 . However, their rate and cycling capabilities are limited by the intrinsic (de-)alloying mechanism. Here, we demonstrate a unique surface redox molecular-level mechanism of P sites on oxidized black phosphorus nanosheets that are strongly coupled with graphene via strong interlayer bonding. These redox-active sites of the oxidized black phosphorus are confined at the amorphorized heterointerface, revealing truly reversible pseudocapacitance (99% of total stored charge at 2,000 mV s-1 )...
December 10, 2018: Nature Materials
Ying Li, Ke-Jia Zhu, Yu-Gui Peng, Wei Li, Tianzhi Yang, He-Xiu Xu, Hong Chen, Xue-Feng Zhu, Shanhui Fan, C-W Qiu
Inspired by the developments in photonic metamaterials, the concept of thermal metamaterials has promised new avenues for manipulating the flow of heat. In photonics, the existence of natural materials with both positive and negative permittivities has enabled the creation of metamaterials with a very wide range of effective parameters. In contrast, in conductive heat transfer, the available range of thermal conductivities in natural materials is far narrower, strongly restricting the effective parameters of thermal metamaterials and limiting possible applications in extreme environments...
December 3, 2018: Nature Materials
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