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Journal of Physics. Condensed Matter: An Institute of Physics Journal

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https://www.readbyqxmd.com/read/29350631/competition-and-coexistence-of-polar-and-non-polar-states-in-sr-sub-1-x-sub-ca-sub-x-sub-tio-sub-3-sub-an-investigation-using-pressure-dependent-raman-spectroscopy
#1
Shekhar Tyagi, Gaurav Sharma, Vasant G Sathe
The competition and cooperation between ferroelectric and antiferrodistortive (AFD) instabilities are studied using pressure dependent Raman spectroscopy on polycrystalline powder samples of Sr1-xCaxTiO3(x=0.0, 0.06, 0.25, 0.35). For x=0.0 composition, broad polar mode is detected in the Raman spectra above 6 GPa, while for x=0.06 composition the polar modes appear well above 9 GPa where the AFD modes showed strong suppression. In x=0.25 and 0.35 composition the application of small pressure results in appearance of strong AFD modes suppressing the polar modes...
January 19, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/29350627/franck-condon-shift-assessment-in-2d-mos-sub-2-sub
#2
Sunny Gupta, Sharmila N Shirodkar, Daniel Kaplan, Venkataraman Swaminathan, Boris I Yakobson
Optical spectroscopy (OS) techniques are often coupled with first-principles density functional theoretical (DFT) calculations for determining the precise influence of defects on the electronic and structural properties of two dimensional (2D) TMDs. Such calculations are carried out presuming there is little or no effect of vibrational transitions on the observed electronic spectrum. However, if the effect of change in vibrational energy [Franck Condon (FC) shift] associated with such a transition is large, it could possibly lead to a different origin for the observed peak...
January 19, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/29350626/high-mobility-in-sub-0-75-sub-ga-sub-0-25-sub-as-quantum-wells-in-an-inas-phonon-lattice
#3
Chong Chen, Stuart N Holmes, Ian Farrer, Harvey E Beere, David A Ritchie
InGaAs based devices are great complements to silicon for CMOS, as they provide an increased carrier saturation velocity, lower operating voltage and reduced power dissipation. In this work we show that In0.75Ga0.25As quantum wells with a high mobility, 15 000 to 20 000 cm2/V.s at ambient temperature, show an InAs-like phonon with an energy of 28.8 meV, frequency of 232 cm-1 that dominates the polar-optical mode scattering from ∼ 70 K to 300 K. The optical phonon frequency is insensitive to the carrier density modulated with a surface gate or LED illumination...
January 19, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/29350625/dynamically-tunable-interface-states-in-1d-graphene-embedded-photonic-crystal-heterostructure
#4
Zhao Huang, Shuaifeng Li, Xin Liu, Degang Zhao, Lei Ye, Xuefeng Zhu, Jianfeng Zang
Optical interface states exhibit promising applications in nonlinear photonics, low-threshold lasing, and surface-wave assisted sensing. However, the further application of interface states in configurable optics is hindered by their limited tunability. Here, we demonstrate a new approach to generate dynamically tunable and angle-resolved interface states using graphene-embedded photonic crystal (GPC) heterostructure device. By combining the GPC structure design with in situ electric doping of graphene, a continuously tunable interface state can be obtained and its tuning range is as wide as the full bandgap...
January 19, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/29350623/exploring-the-role-of-genome-and-structural-ions-in-preventing-viral-capsid-collapse-during-dehydration
#5
Natalia Martín-González, Sofía Guérin, Aritz Durana, Gerardo Martí, Diego M Guérin, Pedro Jose J De Pablo Gomez
Even though viruses evolve mainly in liquid milieu, their horizontal transmission routes often include episodes of dry environment. Along their life cycle, some insect viruses, such as viruses from Dicistroviridae family, withstand dehydrated conditions with yet unknown consequences in their structural stability. Here we use Atomic Force Microscopy to monitor the structural changes of viral particles of Triatoma virus (TrV) after desiccation. Our results demonstrate that TrV capsids preserve their genome inside, conserving their height after exposure to dehydrating conditions, that is in stark contrast with other viruses that expel their genome when desiccated...
January 19, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/29350619/growth-and-lattice-dynamics-of-ultrathin-bao-films-on-pt-001
#6
Veronica Goian, Florian O Schumann, Wolf Widdra
We report on the surface phonons of long-range ordered BaO thin films grown on Pt(001). In the thickness range between 4 and 28 ML, we find unstrained BaO(001)-(1x1) bulk-like terminated films which coincide with a Pt(001)-c(2x2) lattice periodicity. The dipole-active lattice vibrations were determined using high-resolution electron energy loss spectroscopy. For all BaO film thicknesses, a single Fuchs-Kliewer (FK) phonon-polariton is observed. Its intensity increases and its frequency softens with increasing film thickness...
January 19, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/29350202/observation-of-low-temperature-metastable-states-in-complex-camn7o12
#7
Parul Jain, Dipanshu Bansal, Gyaneshwar Sharma, Anupam Bhattacharya, Babita Ingale, Olivier Delaire, Ratnamala Chatterjee
The low temperature magnetic behaviour of the multiferroic quadruple perovskite CaMn7O12 is investigated. The magneto-caloric effect in this material is presented for the first time. Along with the established magnetic transitions, T N1 ~ 90 K and T N2 ~ 45 K, an anomaly at 20 K is observed in our dc magnetization, ac susceptibility and dielectric measurements; below which, an inverse magnetocaloric effect is also observed in our  -ΔS M (T) plots. The neutron scattering measurements show minimal change between 10 K and 30 K in static correlations, but a clear change in energy and linewidth of the magnetic excitations is evident...
January 19, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/29350184/chirality-in-molecular-collision-dynamics
#8
Andrea Lombardi, Federico Palazzetti
Chirality is a phenomenon that permeates the natural world, with implications for atomic and molecular physics, for fundamental forces and for the mechanisms at the origin of the early evolution of life and biomolecular homochirality. The manifestations of chirality in chemistry and biochemistry are numerous, the striking ones being chiral recognition and asymmetric synthesis with important applications in molecular sciences and in industrial and pharmaceutical chemistry. Chiral discrimination phenomena, due to the existence of two enantiomeric forms, very well known in the case of interaction with light, but still nearly disregarded in molecular collision studies...
January 19, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/29345631/role-of-four-fermion-interaction-and-impurity-in-the-states-of-two-dimensional-semi-dirac-materials
#9
Jing Wang
We study the effects of four-fermion interaction and impurity on the low-energy states of two-dimensional semi-Dirac materials by virtue of the unbiased renormalization group approach. The coupled flow equations that govern the energy-dependent evolutions of all correlated interaction parameters are derived after taking into account one-loop corrections from the interplay between four-fermion interaction and impurity. Whether and how four-fermion interaction and impurity influence the low-energy properties of two-dimensional semi-Dirac materials are discreetly explored and addressed attentively...
January 18, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/29345630/completely-flat-two-dimensional-zn-sub-3-sub-o-sub-2-sub-monolayer-with-triangle-and-pentangle-coordinated-networks
#10
Lingbiao Meng, Yingjuan Zhang, Jicheng Zhang, Weidong Wu
Two-dimensional (2D) materials with strictly planar hyper-coordinated motifs are of great importance in fundamental science and potential applications but extremely rare. Here we theoretically design a novel 2D IIB-VIA inorganic system, namely Zn3O2 monolayer, by comprehensive first-principles computations. This Zn3O2 monolayer is composed from highly symmetrical tri-coordinated oxygen and tetra-coordinated zinc, featuring planar and peculiar triangle and pentangle combined bonded network. The newly predicted Zn3O2 monolayer possesses excellent dynamic and thermal stabilities and is also the lowest-energy structure of its 2D space indicated by particle swarm search, supporting its experimentally synthetic viability...
January 18, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/29345628/reversibility-and-intermediate-steps-as-key-tools-for-the-growth-of-extended-ordered-polymers-via-on-surface-synthesis
#11
Marco Di Giovannantonio, Giorgio Contini
Surface-confined polymerization is a bottom-up strategy to create one- and two-dimensional covalent organic nanostructures with a π-conjugated backbone, which are suitable to be employed in real-life electronic devices, due to their high mechanical resistance and electronic charge transport efficiency. This strategy makes it possible to change the properties of the final nanostructures by a careful choice of the monomer architecture (<i>i.e.</i> of its constituent atoms and their spatial arrangement)...
January 18, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/29345624/the-role-of-h-bond-in-the-high-pressure-chemistry-of-model-molecules
#12
Samuele Fanetti, Margherita Citroni, Kamil Dziubek, Marcelo Medre Nobrega, Roberto Bini
Pressure is an extraordinary tool to modify direction and strength of intermolecular interactions with important consequences on the chemical stability of molecular materials. The decrease of the distance among nearest neighbour molecules can give rise to reactive configurations reflecting the crystal arrangement and leading to association processes. In this context, the role of the H-bonds is very peculiar because their usual strengthening with rising pressure not necessarily configures a decrease of the reaction activation energy but, on the contrary, can give rise to an anomalous stability of the system...
January 18, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/29345623/affordable-and-accurate-large-scale-hybrid-functional-calculations-on-gpu-accelerated-supercomputers
#13
Laura E Ratcliff, Augustin Degomme, José A Flores-Livas, Stefan Goedecker, Luigi Genovese
Performing high accuracy hybrid functional calculations for condensed matter systems containing a large number of atoms is at present computationally very demanding or even out of reach if high quality basis sets are used. We present a highly optimized multiple GPU implementation of the exact exchange operator which allows one to perform fast hybrid functional density-functional theory calculations with systematic basis sets without additional approximations for up to a thousand atoms...
January 18, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/29345245/isolating-long-wavelength-fluctuation-from-structural-relaxation-in-two-dimensional-glass-cage-relative-displacement
#14
Hayato Shiba, Peter Keim, Takeshi Kawasaki
It has recently been revealed that long-wavelength fluctuation exists in two- dimensional (2D) glassy systems, having the same origin as that given by the Mermin- Wagner theorem for 2D crystalline solids. Here, extending our recent studies, we discuss the quantification of long-wavelength acoustic fluctuation of a lightly supercooled liquid. This fluctuation can be estimated by subtracting the mean-squared displacement (MSD) of particles relative to its cage, represented by the cage-relative MSD, from the original particle MSD...
January 18, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/29345243/electronic-and-mechanical-response-of-graphene-on-batio-sub-3-sub-at-martensitic-phase-transitions
#15
Tim Verhagen, Vaclav Vales, Martin Kalbac, Jana Vejpravova
Graphene is extremely sensitive to optical, electrical and mechanical stimuli, which cause a significant variation of the band structure, thus physiochemical properties. In our work, we report on changes of strain and doping in graphene grown by chemical vapor deposition (CVD) and transferred onto a BaTiO3(100) (BTO) single-crystal. The BTO is known as a ferroelectric material, which undergoes several thermoelastic martensitic phase transitions when it is cooled from 300 K to 10K. In order to enhance the very weak Raman signal of the graphene monolayer (ML) on the BTO, a 15 nm thin gold layer was deposited on top of the graphene ML to benefit from the surface enhanced Raman scattering (SERS)...
January 18, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/29341957/multiple-tuning-of-magnetic-biskyrmions-using-in-situ-l-tem-in-centrosymmetric-mnniga-alloy
#16
Licong Peng, Ying Zhang, Min He, Bei Ding, Wenhong Wang, Jianqi Li, Jianwang Cai, Shouguo Wang, Guangheng Wu, Baogen Shen
Magnetic skyrmions are topologically protected spin configurations and have recently received growingly attention in magnetic materials. The existence of biskyrmions within a broad temperature range has been identified in our newly-discovered MnNiGa material, promising for potential application in physics and technological study. Here, the biskyrmion microscopic origination from the spin configuration evolution of stripe ground state is experimentally identified. The biskyrmion manipulations based on the influences of the basic microstructures and external factors such as grain boundary confinement, sample thickness, electric current, magnetic field and temperature have been systematically studied by using real-space Lorentz transmission electron microscopy...
January 17, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/29339581/strain-induced-bi-thermoelectricity-in-tapered-carbon-nanotubes
#17
Laith A Algharagholy, Tom Pope, Colin J Lambert
We show that carbon-based nanostructured materials are a novel testbed for controlling thermoelectricity and have the potential to underpin the development of new cost-effective environmentally-friendly thermoelectric materials. In single-molecule junctions, it is known that transport resonances associated with the discrete molecular levels play a key role in the thermoelectric performance, but such resonances have not been exploited in carbon nanotubes (CNTs). Here we study junctions formed from tapered CNTs and demonstrate that such structures possess transport resonances near the Fermi level, whose energetic location can be varied by applying strain, resulting in an ability to tune the sign of their Seebeck coefficient...
January 17, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/29339578/functional-metasurfaces-based-on-metallic-and-dielectric-subwavelength-slits-and-stripes-array
#18
Yinghui Guo, Mingbo Pu, Xiong Li, Xiaoliang Ma, Ping Gao, Yanqin Wang, Xiangang Luo
Starting with the early works of extraordinary optical transmission and total extinction, researchers have been fascinated by the unusual optical properties displayed by metallic holes/slits and subsequently found similar abnormities in dielectric counterparts. Benefiting from the shrinking wavelength of SPPs excited in metallic slits and high refractive index of dielectric stripes, one can realize local phase modulation and approach desired dispersion by engineering the geometries of slits and stripes array...
January 17, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/29339569/experimental-determination-of-configurational-entropy-in-a-two-dimensional-liquid-under-random-pinning
#19
Ian Williams, Francesco Turci, James E Hallett, Peter Crowther, Chiara Cammarota, Giulio Biroli, C Patrick Royall
A quasi two-dimensional colloidal suspension is studied under the influence of immobilisation (pinning) of a random fraction of its particles. We introduce a novel experimental method to perform random pinning and, with the support of numerical simulation, we find that increasing the pinning concentration smoothly arrests the system, with a cross-over from a regime of high mobility and high entropy to a regime of low mobility and low entropy. At the local level, we study fluctuations in area fraction and concentration of pins and map them to entropic structural signatures and local mobility, obtaining a measure for the local entropic fluctuations of the experimental system...
January 17, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/29337698/fe-and-co-nmr-studies-of-magnetoelectric-co2-y-type-hexaferrite-bscfao
#20
Baeksoon Choi, Sangil Kwon, Soonchil Lee, Chang Bae Park, Kwang Woo Shin, Keehoon Kim
The Fe3+ and Co2+ NMR spectra for Ba0.3Sr1.7Co2(Fe0.96Al0.04)12O22 (BSCFAO) and Ba0.3Sr1.7Co2Fe12O22 (BSCFO) were obtained in a zero magnetic field at a low temperature. We observed change in the enhancement effect of the NMR signals depending on the setting field, which was varied when applied along the b-axis and then turned off before the measurement was taken. The experimental results indicate that the magnetic structure changes from an alternating longitudinal cone to a transverse cone when the setting field is 250 mT...
January 16, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
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