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Articles 1  30 of 89
FullText Articles in Physics
Emergent Ising Degrees Of Freedom Above A DoubleStripe Magnetic Ground State, Guanghua Zhang, Rebecca Flint
Emergent Ising Degrees Of Freedom Above A DoubleStripe Magnetic Ground State, Guanghua Zhang, Rebecca Flint
Ames Laboratory Accepted Manuscripts
Doublestripe magnetism [ Q = ( π / 2 , π / 2 ) ] has been proposed as the magnetic ground state for both the irontelluride and BaTi 2 Sb 2 O families of superconductors. Doublestripe order is captured within a J 1 − J 2 − J 3 Heisenberg model in the regime J 3 ≫ J 2 ≫ J 1 . Intriguingly, besides breaking spinrotational symmetry, the groundstate manifold has three additional Ising degrees of freedom associated with bond ordering. Via their coupling to the lattice, they give rise to an orthorhombic distortion and to two nonuniform lattice distortions with wave vector ( π , π ) . Because the ground state is fourfold ...
Texture Development And Coercivity Enhancement In Cast Alnico 9 Magnets, Wenyong Zhang, Shah Valloppilly, Xingzhong Li, Lanping Yue, Ralph Skomski, Iver E. Anderson, Matthew J. Kramer, Wei Tang, Jeff Shield, David J. Sellmyer
Texture Development And Coercivity Enhancement In Cast Alnico 9 Magnets, Wenyong Zhang, Shah Valloppilly, Xingzhong Li, Lanping Yue, Ralph Skomski, Iver E. Anderson, Matthew J. Kramer, Wei Tang, Jeff Shield, David J. Sellmyer
Ames Laboratory Accepted Manuscripts
The effect of Y addition and magnetic field on texture and magnetic properties of arcmelted alnico 9 magnets has been investigated. Small additions of Y (1.5 wt.%) develop a (200) texture for the arcmelted alnico 9 magnet. Such a texture is hard to form in cast samples. To achieve this goal, we set up a highfield annealing system with a maximum operation temperature of 1250 °C. This system enabled annealing in a field of 45 kOe with subsequent draw annealing for the solutionized buttons; we have been able to substantially increase remanence ratio and coercivity, from 0.70 and ...
Influence Of Classical Anisotropy Fields On The Properties Of Heisenberg Antiferromagnets Within Unified Molecular Field Theory, David C. Johnston
Influence Of Classical Anisotropy Fields On The Properties Of Heisenberg Antiferromagnets Within Unified Molecular Field Theory, David C. Johnston
Ames Laboratory Accepted Manuscripts
A comprehensive study of the influence of classical anisotropy fields on the magnetic properties of Heisenberg antiferromagnets within unified molecular field theory versus temperature T , magnetic field H , and anisotropy field parameter h A 1 is presented for systems comprised of identical crystallographicallyequivalent local moments. The anisotropy field for collinear z axis antiferromagnetic (AFM) ordering is constructed so that it is aligned in the direction of each ordered and/or fieldinduced thermalaverage moment with a magnitude proportional to the moment, whereas that for XY anisotropy is defined to be in the direction of the projection of the moment onto the ...
R14(Au, M)51 (R = Y, La−Nd, Sm−Tb, Ho, Er, Yb, Lu; M = Al, Ga, Ge, In,Sn, Sb, Bi): Stability Ranges And Site Preference In The Gd14ag51 Structure Type, Chris Celania, Volodymyr Smetana, Alessia Provino, Pietro Manfrinetti, AnjaVerena Mudring
R14(Au, M)51 (R = Y, La−Nd, Sm−Tb, Ho, Er, Yb, Lu; M = Al, Ga, Ge, In,Sn, Sb, Bi): Stability Ranges And Site Preference In The Gd14ag51 Structure Type, Chris Celania, Volodymyr Smetana, Alessia Provino, Pietro Manfrinetti, AnjaVerena Mudring
Ames Laboratory Accepted Manuscripts
Twenty new ternary representatives of the Gd14Ag51 structure type have been synthesized within the RAuM family (R = Y, La–Nd, Sm–Tb, Ho, Er, Yb, Lu; M = Al, Ga, Ge, In, Sn, Sb, Bi) using solid state synthesis techniques. The list of post transition metals (M) involved in the formation of this type of structure could be augmented by five new representatives. All compounds crystallize in the hexagonal space group P6/m (#175) with the unit cell ranges of a = 12.3136(2)–12.918(1) Å and c = 8.9967(3)–9.385(1) Å, and incorporate different ...
Nematicity, Magnetism And Superconductivity In Fese, Anna E. Böhmer, Andreas Kreisel
Nematicity, Magnetism And Superconductivity In Fese, Anna E. Böhmer, Andreas Kreisel
Ames Laboratory Accepted Manuscripts
Ironbased superconductors are well known for their complex interplay between structure, magnetism and superconductivity. FeSe offers a particularly fascinating example. This material has been intensely discussed because of its extended nematic phase, whose relationship with magnetism is not obvious. Superconductivity in FeSe is highly tunable, with the superconducting transition temperature, T c, ranging from 8 K in bulk single crystals at ambient pressure to almost 40 K under pressure or in intercalated systems, and to even higher temperatures in thin films. In this topical review, we present an overview of nematicity, magnetism and superconductivity, and discuss the interplay of these ...
Local Nematic Susceptibility In Stressed Bafe 2 As 2 From Nmr Electric Field Gradient Measurements, T. Kissikov, R. Sarkar, M. Lawson, B. T. Bush, Erik I. Timmons, Makariy A. Tanatar, Ruslan Prozorov, S. L. Bud’Ko, Paul C. Canfield, R. M. Fernandes, W. F. Goh, W. E. Pickett, N. J. Curro
Local Nematic Susceptibility In Stressed Bafe 2 As 2 From Nmr Electric Field Gradient Measurements, T. Kissikov, R. Sarkar, M. Lawson, B. T. Bush, Erik I. Timmons, Makariy A. Tanatar, Ruslan Prozorov, S. L. Bud’Ko, Paul C. Canfield, R. M. Fernandes, W. F. Goh, W. E. Pickett, N. J. Curro
Ames Laboratory Accepted Manuscripts
The electric field gradient (EFG) tensor at the 75As site couples to the orbital occupations of the As porbitals and is a sensitive probe of local nematicity in BaFe2As2. We use nuclear magnetic resonance to measure the nuclear quadrupolar splittings and find that the EFG asymmetry responds linearly to the presence of a strain field in the paramagnetic phase. We extract the nematic susceptibility from the slope of this linear response as a function of temperature and find that it diverges near the structural transition, in agreement with other measures of the bulk nematic susceptibility. Our work establishes an alternative ...
Diffusion Of TwoDimensional Epitaxial Clusters On Metal (100) Surfaces: Facile Versus NucleationMediated Behavior And Their Merging For Larger Sizes, King C. Lai, DaJiang Liu, James W. Evans
Diffusion Of TwoDimensional Epitaxial Clusters On Metal (100) Surfaces: Facile Versus NucleationMediated Behavior And Their Merging For Larger Sizes, King C. Lai, DaJiang Liu, James W. Evans
Ames Laboratory Accepted Manuscripts
For diffusion of twodimensional homoepitaxial clusters of N atoms on metal (100) surfaces mediated by edge atom hopping, macroscale continuum theory suggests that the diffusion coefficient scales like DN∼N−β with β=3/2. However, we find quite different and diverse behavior in multiple size regimes. These include: (i) facile diffusion for small sizes N<9; (ii) slow nucleationmediated diffusion with small β<1 for “perfect” sizes N=Np=L2 or L(L+1), for L=3,4, ... having unique groundstate shapes, for moderate sizes 9≤N≤O(102); the same also applies for N=Np+3, Np+4, ...(iii) facile diffusion but with large β>2 for N=Np+1 and Np+2 also for moderate sizes 9≤N≤O(102); (iv) merging of the above distinct branches and subsequent anomalous scaling with 1≲β<3/2, reflecting the quasifacetted structure of clusters, for larger N=O(102) to N=O(103); (v) classic scaling with β=3/2 for very large N=O(103) and above. The specified size ranges apply for typical model parameters. We focus on the moderate size regime where we show that diffusivity cycles quasiperiodically from the slowest branch for Np+3 (not Np) to the fastest branch for Np+1. Behavior is quantified by kinetic Monte Carlo simulation of an appropriate stochastic latticegas model. However, precise analysis must account for a strong enhancement of diffusivity for short time increments due to back correlation in the cluster motion. Further understanding of this enhancement, of anomalous size scaling behavior, and of the merging of various branches, is facilitated by combinatorial analysis of the number of the groundstate and lowlying excited state cluster configurations, and also of kink populations.
FirstPrinciples Study On The Electronic, Optical, And Transport Properties Of Monolayer Α And ΒGese, Yuanfeng Xu, Hao Zhang, Hezhu Shao, Gang Ni, Jing Li, Hongliang Lu, Rongjun Zhang, Bo Peng, Yongyuan Zhu, Heyuan Zhu, Costas M. Soukoulis
FirstPrinciples Study On The Electronic, Optical, And Transport Properties Of Monolayer Α And ΒGese, Yuanfeng Xu, Hao Zhang, Hezhu Shao, Gang Ni, Jing Li, Hongliang Lu, Rongjun Zhang, Bo Peng, Yongyuan Zhu, Heyuan Zhu, Costas M. Soukoulis
Ames Laboratory Accepted Manuscripts
The extraordinary properties and the novel applications of black phosphorene induce the research interest in the monolayer groupIV monochalcogenides. Here using firstprinciples calculations, we systematically investigate the electronic, transport, and optical properties of monolayer alpha and betaGeSe, revealing a direct band gap of 1.61 eV for monolayer alphaGeSe and an indirect band gap of 2.47 eV for monolayer betaGeSe. For monolayer betaGeSe, the electronic/hole transport is anisotropic, with an extremely high electron mobility of 2.93 x 10(4) cm(2)/Vs along the armchair direction, comparable to that of black phosphorene. Furthermore, for betaGeSe, robust band ...
Ionic Depletion At The Crystalline Gibbs Layer Of PegCapped Gold Nanoparticle Brushes At Aqueous Surfaces, Wenjie Wang, Honghu Zhang, Surya Mallapragada, Alex Travesset, David Vaknin
Ionic Depletion At The Crystalline Gibbs Layer Of PegCapped Gold Nanoparticle Brushes At Aqueous Surfaces, Wenjie Wang, Honghu Zhang, Surya Mallapragada, Alex Travesset, David Vaknin
Ames Laboratory Accepted Manuscripts
In situ surfacesensitive xray diffraction and grazing incidence xray fluorescence spectroscopy (GIXFS) methods are combined to determine the ionic distributions across the liquid/vapor interfaces of thiolatedpolyethyleneglycol–capped gold nanoparticle (PEGAuNP) solutions. Induced by the addition of salts (i.e., Cs2SO4) to PEGAuNPs solutions, twodimensional hexagonal lattices of PEGAuNPs form spontaneously at the aqueous surfaces, as is demonstrated by xray reflectivity and grazing incidence smallangle xray scattering. By taking advantage of element specificity with the GIXFS method, we find that the cation Cs+ concentration at the crystalline film is significantly reduced in parts of the PEGAuNP film compared with that ...
A Molecular DebyeHückel Theory Of Solvation In Polar Fluids: An Extension Of The Born Model, Tiejun Xiao, Xueyu Song
A Molecular DebyeHückel Theory Of Solvation In Polar Fluids: An Extension Of The Born Model, Tiejun Xiao, Xueyu Song
Ames Laboratory Accepted Manuscripts
A dielectric response theory of solvation beyond the conventional Born model for polar fluids is presented. The dielectric response of a polar fluid is described by a Born response mode and a linear combination of DebyeHückellike response modes that capture the nonlocal response of polar fluids. The Born mode is characterized by a bulk dielectric constant, while a DebyeHückel mode is characterized by its corresponding Debye screening length. Both the bulk dielectric constant and the Debye screening lengths are determined from the bulk dielectric function of the polar fluid. The linear combination coefficients of the response modes are evaluated in ...
Measurements Of Azimuthal Anisotropy And ChargedParticle Multiplicity In D + Au Collisions At √Snn = 200, 62.4, 39, And 19.6 Gev, C. Aidala, Nicole J. Apadula, Nels J. Hotvedt, John G. Lajoie, Alexandre Lebedev, S. H. Lee, Craig Ogilvie, Milap R. Patel, Timothy T. Rinn, Marzia Rosati, Jonathan C. Runchey, Abhisek Sen, M. Shimomura, Arbin Timilsina, Et Al., Phenix Collaboration
Measurements Of Azimuthal Anisotropy And ChargedParticle Multiplicity In D + Au Collisions At √Snn = 200, 62.4, 39, And 19.6 Gev, C. Aidala, Nicole J. Apadula, Nels J. Hotvedt, John G. Lajoie, Alexandre Lebedev, S. H. Lee, Craig Ogilvie, Milap R. Patel, Timothy T. Rinn, Marzia Rosati, Jonathan C. Runchey, Abhisek Sen, M. Shimomura, Arbin Timilsina, Et Al., Phenix Collaboration
Physics and Astronomy Publications
We present measurements of the elliptic flow (v(2)) as a function of transverse momentum (p(T)), pseudorapidity (eta), and centrality in d + Au collisions at root s(NN) = 200, 62.4, 39, and 19.6 GeV. The beamenergy scan of d + Au collisions provides a testing ground for the onset of flow signatures in small collision systems. We measure a nonzero v(2) signal at all four collision energies, which, at midrapidity and low p(T), is consistent with predictions from viscous hydrodynamic models. Comparisons with calculations from parton transport models (based on the AMPT Monte Carlo generator) show ...
BMeson Production At Forward And Backward Rapidity In P+P And Cu+Au Collisions At √Snn=200 Gev, C. Aidala, Nicole J. Apadula, John C. Hill, Nels J. Hotvedt, Todd Kempel, John G. Lajoie, Alexandre Lebedev, S. H. Lee, Craig Ogilvie, Milap R. Patel, Joshua Perry, Timothy T. Rinn, Marzia Rosati, Jonathan C. Runchey, Abhisek Sen, Alex Shaver, M. Shimomura, Arbin Timilsina, Shawn Whitaker, Et Al., Phenix Collaboration
BMeson Production At Forward And Backward Rapidity In P+P And Cu+Au Collisions At √Snn=200 Gev, C. Aidala, Nicole J. Apadula, John C. Hill, Nels J. Hotvedt, Todd Kempel, John G. Lajoie, Alexandre Lebedev, S. H. Lee, Craig Ogilvie, Milap R. Patel, Joshua Perry, Timothy T. Rinn, Marzia Rosati, Jonathan C. Runchey, Abhisek Sen, Alex Shaver, M. Shimomura, Arbin Timilsina, Shawn Whitaker, Et Al., Phenix Collaboration
Physics and Astronomy Publications
The fraction of J/psi mesons which come from Bmeson decay, FB > J/psi is measured for J/psi rapidity 1.2 < y < 2.2 and p(T) > 0 in p + p and Cu+Au collisions at root s(NN) = 200 GeV with the PHENIX detector. The extracted fraction is FB > J/psi = 0.025 +/ 0.006 (stat) +/ 0.010(syst) for p + p collisions. For Cu+Au collisions, FB > J/psi is 0.094 +/ 0.028(stat) +/ 0.037(syst) in the Augoing direction (2.2 < y < 1.2) and 0.089 +/ 0.026(stat) +/ 0.040(syst) in the Cugoing direction (1.2 < y < 2.2). The nuclear modification factor, RCuAu,of B mesons in Cu+Au collisions is consistent with binary scaling of measured yields in p + p at both forward and backward rapidity.
Nmr Study Of The New Magnetic Superconductor Cak ( Fe 0.951 Ni 0.049 ) 4 As 4 : Microscopic Coexistence Of The Hedgehog SpinVortex Crystal And Superconductivity, QingPing Ding, William R. Meier, A. E. Böhmer, S. L. Bud’Ko, Paul C. Canfield, Yuji Furukawa
Nmr Study Of The New Magnetic Superconductor Cak ( Fe 0.951 Ni 0.049 ) 4 As 4 : Microscopic Coexistence Of The Hedgehog SpinVortex Crystal And Superconductivity, QingPing Ding, William R. Meier, A. E. Böhmer, S. L. Bud’Ko, Paul C. Canfield, Yuji Furukawa
Ames Laboratory Accepted Manuscripts
The coexistence of a newtype antiferromagnetic (AFM) state, the socalled hedgehog spinvortex crystal (SVC), and superconductivity (SC) is evidenced by an 75 As nuclear magnetic resonance study on singlecrystalline CaK ( Fe 0.951 Ni 0.049 ) 4 As 4 . The hedgehog SVC order is clearly demonstrated by the direct observation of internal magnetic induction along the c axis at the As1 site (close to K) and a zero net internal magnetic induction at the As2 site (close to Ca) below an AFM ordering temperature T N ∼ 52 K. The nuclear spinlattice relaxation rate 1 / T 1 shows a distinct decrease ...
Optical Absorption Properties Of Ge2–44 And PDoped Ge Nanoparticles, Wei Qin, WenCai Lu, LiZhen Zhao, KaiMing Ho, CaiZhuang Wang
Optical Absorption Properties Of Ge2–44 And PDoped Ge Nanoparticles, Wei Qin, WenCai Lu, LiZhen Zhao, KaiMing Ho, CaiZhuang Wang
Ames Laboratory Accepted Manuscripts
The optical absorption properties of noncrystalline and crystalline Ge nanoparticles with the sizes from ∼2.5 to 15 Å have been studied at the B3LYP/631G level using timedependent density functional theory. Hydrogen passivation and phosphorus doping on some selected Ge nanoparticles were also calculated. With the increase of cluster size, the optical absorption spectra of the noncrystalline Ge nanoparticles change from many peaks to a continuous broad band and at the same time exhibit a systematic redshift. Doping phosphorus also causes the absorption spectra to shift toward the lower energy region for both noncrystalline and crystalline Ge nanoparticles. The ...
Communication: Diverse Nanoscale Cluster Dynamics: Diffusion Of 2d Epitaxial Clusters, King C. Lai, James W. Evans, DaJiang Liu
Communication: Diverse Nanoscale Cluster Dynamics: Diffusion Of 2d Epitaxial Clusters, King C. Lai, James W. Evans, DaJiang Liu
Ames Laboratory Accepted Manuscripts
The dynamics of nanoscale clusters can be distinct from macroscale behavior described by continuum formalisms. For diffusion of 2D clusters of N atoms in homoepitaxial systems mediated by edge atom hopping, macroscale theory predicts simple monotonic size scaling of the diffusion coefficient, DN ∼ N−β, with β = 3/2. However, modeling for nanoclusters on metal(100) surfaces reveals that slow nucleationmediated diffusion displaying weak size scaling β < 1 occurs for “perfect” sizes Np = L2 and L(L+1) for integer L = 3,4,… (with unique square or nearsquare ground state shapes), and also for Np+3, Np+4,…. In contrast, fast facile nucleationfree diffusion displaying strong size scaling β ≈ 2.5 occurs for sizes Np+1 and Np+2. DN versus N oscillates strongly between the slowest branch (for Np+3) and the fastest branch (for Np+1). All branches merge for N = O(102), but macroscale behavior is only achieved for much larger N = O(103). This analysis reveals the unprecedented diversity of behavior on the nanoscale.
In Situ Investigation Of Magnetism In Metastable Phases Of Levitated Fe83b17 During Solidification, D. G. Quirinale, D. Messina, G. E. Rustan, Andreas Kreyssig, Ruslan Prozorov, Alan I. Goldman
In Situ Investigation Of Magnetism In Metastable Phases Of Levitated Fe83b17 During Solidification, D. G. Quirinale, D. Messina, G. E. Rustan, Andreas Kreyssig, Ruslan Prozorov, Alan I. Goldman
Ames Laboratory Accepted Manuscripts
In situ measurements of structure, density, and magnetization on samples of Fe83B17 using an electrostatic levitation furnace allow us to identify and correlate the magnetic and structural transitions in this system during its complex solidification process. In particular, we identify magnetic ordering in the metastable Fe23B6/ fcc Fe coherently grown structures and primitive tetragonal Fe3B metastable phase in addition to characterizing the equilibrium Fe2B phase. Our measurements demonstrate that the incorporation of a tunneldiode oscillator circuit within an electrostatic levitation furnace enables investigations of the physical properties of hightemperature metastable structures.
ThicknessDependent Energetics For Pb Adatoms On LowIndex Pb Nanofilm Surfaces: FirstPrinciples Calculations, Wei Li, Li Huang, Raj Ganesh S. Pala, GuangHong Lu, Feng Liu, James W. Evans, Yong Han
ThicknessDependent Energetics For Pb Adatoms On LowIndex Pb Nanofilm Surfaces: FirstPrinciples Calculations, Wei Li, Li Huang, Raj Ganesh S. Pala, GuangHong Lu, Feng Liu, James W. Evans, Yong Han
Physics and Astronomy Publications
Adsorption, interaction, and diffusion of adatoms on surfaces control growth and relaxation of epitaxial nanostructures and nanofilms. Previous reports of key diffusion barriers for Pb diffusion on lowindex Pb surfaces are limited in scope and accuracy. Thus, we apply density functional theory (DFT) to calculate the adsorption and diffusion energetics for a Pb adatom on Pb(111), Pb(100), and Pb(110) nanofilms with different thicknesses. We find that these quantities exhibit damped oscillatory variation with increasing film thickness. For Pb(111) films, energetics along the minimum energy path for Pb adatom diffusion between adjacent fcc and hcp sites varies ...
Phase Transitions In Mgsio3 PostPerovskite In SuperEarth Mantles, Koichiro Umemoto, Renata M. Wentzcovitch, Shunqing Wu, Min Ji, CaiZhuang Wang, KaiMing Ho
Phase Transitions In Mgsio3 PostPerovskite In SuperEarth Mantles, Koichiro Umemoto, Renata M. Wentzcovitch, Shunqing Wu, Min Ji, CaiZhuang Wang, KaiMing Ho
Ames Laboratory Accepted Manuscripts
The highest pressure form of the major Earthforming mantle silicate is MgSiO3 postperovskite (PPv). Understanding the fate of PPv at TPa pressures is the first step for understanding the mineralogy of superEarthstype exoplanets, arguably the most interesting for their similarities with Earth. Modeling their internal structure requires knowledge of stable mineral phases, their properties under compression, and major element abundances. Several studies of PPv under extreme pressures support the notion that a sequence of pressure induced dissociation transitions produce the elementary oxides SiO2 and MgO as the ultimate aggregation form at ∼3 TPa. However, none of these studies have addressed ...
Emergent Bloch Excitations In Mott Matter, Nicola Lanatà, TsungHan Lee, YongXin Yao, Vladimir Dobrosavljević
Emergent Bloch Excitations In Mott Matter, Nicola Lanatà, TsungHan Lee, YongXin Yao, Vladimir Dobrosavljević
Ames Laboratory Accepted Manuscripts
We develop a unified theoretical picture for excitations in Mott systems, portraying both the heavy quasiparticle excitations and the Hubbard bands as features of an emergent Fermi liquid state formed in an extended Hilbert space, which is nonperturbatively connected to the physical system. This observation sheds light on the fact that even the incoherent excitations in strongly correlated matter often display a welldefined Bloch character, with pronounced momentum dispersion. Furthermore, it indicates that the Mott point can be viewed as a topological transition, where the number of distinct dispersing bands displays a sudden change at the critical point. Our results ...
Broadband Mixing Of PtSymmetric And PtBroken Phases In Photonic Heterostructures With A OneDimensional Loss/Gain Bilayer, Ege Özgün, Andriy E. Serebryannikov, Ekmel Ozbay, Costas M. Soukoulis
Broadband Mixing Of PtSymmetric And PtBroken Phases In Photonic Heterostructures With A OneDimensional Loss/Gain Bilayer, Ege Özgün, Andriy E. Serebryannikov, Ekmel Ozbay, Costas M. Soukoulis
Ames Laboratory Accepted Manuscripts
Combining loss and gain components in one photonic heterostructure opens a new route to efficient manipulation by radiation, transmission, absorption, and scattering of electromagnetic waves. Therefore, loss/gain structures enabling PTsymmetric and PTbroken phases for eigenvalues have extensively been studied in the last decade. In particular, translation from one phase to another, which occurs at the critical point in the twochannel structures with onedimensionalloss/gain components, is often associated with oneway transmission. In this report, broadband mixing of the PTsymmetric and PTbroken phases for eigenvalues is theoretically demonstrated in heterostructures with four channels obtained by combining a onedimensional loss/gain ...
Electromagnetic Shielding Effectiveness Of 3d Printed Polymer Composites, Z. Viskadourakis, K. C. Vasilopoulos, E. N. Economou, Costas M. Soukoulis, G. Kenanakis
Electromagnetic Shielding Effectiveness Of 3d Printed Polymer Composites, Z. Viskadourakis, K. C. Vasilopoulos, E. N. Economou, Costas M. Soukoulis, G. Kenanakis
Ames Laboratory Accepted Manuscripts
We report on preliminary results regarding the electromagnetic shielding effectiveness of various 3D printed polymeric composite structures. All studied samples were fabricated using 3D printing technology, following the fused deposition modeling approach, using commercially available filaments as starting materials. The electromagnetic shielding performance of the fabricated 3D samples was investigated in the so called Cband of the electromagnetic spectrum (3.5–7.0 GHz), which is typically used for longdistance radio telecommunications. We provide evidence that 3D printing technology can be effectively utilized to prepare operational shields, making them promising candidates for electromagnetic shielding applications for electronic devices.
Coexistence Of TypeIi Dirac Point And Weak Topological Phase In Pt 3 Sn, Minsung Kim, CaiZhuang Wang, KaiMing Ho
Coexistence Of TypeIi Dirac Point And Weak Topological Phase In Pt 3 Sn, Minsung Kim, CaiZhuang Wang, KaiMing Ho
Ames Laboratory Accepted Manuscripts
Intriguing topological phases may appear in both insulating and semimetallic states. Topological insulators exhibit topologically nontrivial band inversion, while topological Dirac/Weyl semimetals show “relativistic” linear band crossings. Here, we report an unusual topological state of Pt3Sn, where the two topological features appear simultaneously. Based on firstprinciples calculations, we show that Pt3Sn is a threedimensional weak topological semimetal with topologically nontrivial band inversion between the valence and conduction bands, where the band structure also possesses typeII Dirac points at the boundary of two electron pockets. The formation of the Dirac points can be understood in terms of the representations of ...
Heisenberg Model Analysis On Inelastic Powder Neutron Scattering Data Using Parent And K Doped Bamn2as2 Samples, Mehmet Ramazanoglu, Aashish Sapkota, Abhishek Pandey, Jagat Lamsal, Douglas L. Abernathy, Jennifer L. Niedziela, Matthew B. Stone, R. Salci, D. A. Acar, F. O. Oztirpan, Şener Ozonder, Andreas Kreyssig, Alan I. Goldman, David C. Johnston, Robert J. Mcqueeney
Heisenberg Model Analysis On Inelastic Powder Neutron Scattering Data Using Parent And K Doped Bamn2as2 Samples, Mehmet Ramazanoglu, Aashish Sapkota, Abhishek Pandey, Jagat Lamsal, Douglas L. Abernathy, Jennifer L. Niedziela, Matthew B. Stone, R. Salci, D. A. Acar, F. O. Oztirpan, Şener Ozonder, Andreas Kreyssig, Alan I. Goldman, David C. Johnston, Robert J. Mcqueeney
Ames Laboratory Accepted Manuscripts
Low temperature powder inelastic neutron scattering measurements were performed on three different powder samples; parent BaMn2As2,12.5% Kdoped Ba0.875K0.125Mn2As2 and 25% Kdoped Ba(0.75)K0.25Mn2As2. The Heisenberg Model involving J1‐J2‐Jz coupling constants were compared to the data by a powder integration routine using Monte Carlo integration methods. The best magnetic parameters were selected using a chisquare test where model intensities were compared to the full (q,E) dependence of magnetic scattering. A key step to this analysis is the characterization of the background which is formed mostly by phonon scattering intensities along with ...
Subsurface Bending And Reorientation Of Tilted Vortex Lattices In Bulk Isotropic Superconductors Due To CoulombLike Repulsion At The Surface, E. Herrera, I. Guillamon, J. A. Galvis, A. Correa, A. Fente, S. Vieira, H. Suderow, A. Yu. Martynovich, Vladimir G. Kogan
Subsurface Bending And Reorientation Of Tilted Vortex Lattices In Bulk Isotropic Superconductors Due To CoulombLike Repulsion At The Surface, E. Herrera, I. Guillamon, J. A. Galvis, A. Correa, A. Fente, S. Vieira, H. Suderow, A. Yu. Martynovich, Vladimir G. Kogan
Ames Laboratory Accepted Manuscripts
We study vortex lattices (VLs) in superconducting weakpinning plateletlike single crystals of β−Bi2Pdin tilted magnetic fields with a scanning tunneling microscope. We show that vortices exit the sample perpendicular to the surface and are thus bent beneath the surface. The structure and orientation of the tilted VLs in the bulk are, for large tilt angles, strongly affected by Coulombtype intervortex repulsion at the surface due to stray magnetic fields.
Electromagnetic Fields From Quantum Sources In HeavyIon Collisions, Balthazar Peroutka, Kirill Tuchin
Electromagnetic Fields From Quantum Sources In HeavyIon Collisions, Balthazar Peroutka, Kirill Tuchin
Physics and Astronomy Publications
We compute the electromagnetic field created by an ultrarelativistic charged particle in vacuum at distances comparable to the particle Compton wavelength. The wave function of the particle is governed by the KleinGordon equation, for a scalar particle, or the Dirac equation, for a spinhalf particle. The produced electromagnetic field is essentially different in magnitude and direction from the Coulomb field, induced by a classical point charge, due to the quantum diffusion effect. Thus, a realistic computation of the electromagnetic field produced in heavyion collisions must be based upon the full quantum treatment of the valence quarks.
Electronic, Magnetic, And Magnetocrystalline Anisotropy Properties Of Light Lanthanides, T. A. Hackett, D. J. Baldwin, Durga Paudyal
Electronic, Magnetic, And Magnetocrystalline Anisotropy Properties Of Light Lanthanides, T. A. Hackett, D. J. Baldwin, Durga Paudyal
Ames Laboratory Accepted Manuscripts
Theoretical understanding of interactions between localized and mobile electrons and the crystal environment in light lanthanides is important because of their key role in much needed magnetic anisotropy in permanent magnet materials that have a great impact in automobile and wind turbine applications. We report electronic, magnetic, and magnetocrystalline properties of these basic light lanthanide elements studied from advanced density functional theory (DFT) calculations. We find that the inclusion of onsite 4f electron correlation and spin orbit coupling within the fullpotential band structure is needed to understand the unique magnetocrystalline properties of these light lanthanides. The onsite electron correlation, spin ...
SpinDensity Fluctuations And The FluctuationDissipation Theorem In 3d Ferromagnetic Metals, A. L. Wysocki, V. N. Valmispild, S. Sharma, J. K. Dewhurst, E. K.U. Gross, A. I. Lichtenstein, Vladimir P. Antropov
SpinDensity Fluctuations And The FluctuationDissipation Theorem In 3d Ferromagnetic Metals, A. L. Wysocki, V. N. Valmispild, S. Sharma, J. K. Dewhurst, E. K.U. Gross, A. I. Lichtenstein, Vladimir P. Antropov
Ames Laboratory Accepted Manuscripts
Spatial and time scales of spindensity fluctuations (SDFs) were analyzed in 3d ferromagnets using ab initio linearresponse calculations of complete wavevector and energy dependence of the dynamic spin susceptibility tensor. We demonstrate that SDFs are spread continuously over the entire Brillouin zone and while the majority of them reside within the 3d bandwidth, a significant amount comes from much higher energies. A validity of the adiabatic approximation in spin dynamics is discussed. The SDF spectrum is shown to have two main constituents: a minor lowenergy spinwave contribution and a much larger highenergy component from more localized excitations. Using the fluctuationdissipation ...
Nmr Evidence For Static Local Nematicity And Its Cooperative Interplay With LowEnergy Magnetic Fluctuations In Fese Under Pressure, Paul W. Wiecki, A. E. Böhmer, Serguei L. Bud’Ko, Paul C. Canfield, Yuji Furukawa
Nmr Evidence For Static Local Nematicity And Its Cooperative Interplay With LowEnergy Magnetic Fluctuations In Fese Under Pressure, Paul W. Wiecki, A. E. Böhmer, Serguei L. Bud’Ko, Paul C. Canfield, Yuji Furukawa
Ames Laboratory Accepted Manuscripts
We present 77Se NMR measurements on singlecrystalline FeSe under pressures up to 2 GPa. Based on the observation of the splitting and broadening of the NMR spectrum due to structural twin domains, we discovered that static, local nematic ordering exists well above the bulk nematic ordering temperature, T s . The static, local nematic order and the lowenergy stripetype antiferromagnetic spin fluctuations, as revealed by NMR spinlattice relaxation rate measurements, are both insensitive to pressure application. These NMR results provide clear evidence for the microscopic cooperation between magnetism and local nematicity in FeSe.
Determining The Vortex Tilt Relative To A Superconductor Surface, Vladimir G. Kogan, J. R. Kirtley
Determining The Vortex Tilt Relative To A Superconductor Surface, Vladimir G. Kogan, J. R. Kirtley
Ames Laboratory Accepted Manuscripts
It is of interest to determine the exit angle of a vortex from a superconductor surface, since this affects the intervortex interactions and their consequences. Two ways to determine this angle are to image the vortex magnetic fields above the surface, or the vortex core shape at the surface. In this work we evaluate the field h(x,y,z) above a flat superconducting surface x,y and the currents J(x,y) at that surface for a straight vortex tilted relative to the normal to the surface, for both the isotropic and anisotropic cases. In principle, these results can ...
Collapsed Tetragonal Phase Transition In Laru2p2, Gil Drachuck, Aashish Sapkota, Wageesha T. Jayasekara, Karunakar Kothapalli, Sergey L. Bud’Ko, Alan I. Goldman, Andreas Kreyssig, Paul C. Canfield
Collapsed Tetragonal Phase Transition In Laru2p2, Gil Drachuck, Aashish Sapkota, Wageesha T. Jayasekara, Karunakar Kothapalli, Sergey L. Bud’Ko, Alan I. Goldman, Andreas Kreyssig, Paul C. Canfield
Ames Laboratory Accepted Manuscripts
The structural properties of LaRu2P2 under external pressure have been studied up to 14 GPa, employing highenergy xray diffraction in a diamondanvil pressure cell. At ambient conditions, LaRu2P2 (I4/mmm) has a tetragonal structure with a bulk modulus of B=105(2) GPa and exhibits superconductivity at Tc=4.1 K. With the application of pressure, LaRu2P2 undergoes a phase transition to a collapsed tetragonal (cT) state with a bulk modulus of B=175(5) GPa. At the transition, the clattice parameter exhibits a sharp decrease with a concurrent increase of the alattice parameter. The cT phase transition in ...