Open Access. Powered by Scholars. Published by Universities.®

Condensed Matter Physics Commons

Open Access. Powered by Scholars. Published by Universities.®

2607 Full-Text Articles 3143 Authors 345609 Downloads 79 Institutions

All Articles in Condensed Matter Physics

Faceted Search

2607 full-text articles. Page 1 of 82.

Ionic Depletion At The Crystalline Gibbs Layer Of Peg-Capped Gold Nanoparticle Brushes At Aqueous Surfaces, Wenjie Wang, Honghu Zhang, Surya Mallapragada, Alex Travesset, David Vaknin 2018 Ames Laboratory

Ionic Depletion At The Crystalline Gibbs Layer Of Peg-Capped Gold Nanoparticle Brushes At Aqueous Surfaces, Wenjie Wang, Honghu Zhang, Surya Mallapragada, Alex Travesset, David Vaknin

Surya K. Mallapragada

In situ surface-sensitive x-ray diffraction and grazing incidence x-ray fluorescence spectroscopy (GIXFS) methods are combined to determine the ionic distributions across the liquid/vapor interfaces of thiolated-polyethylene-glycol–capped gold nanoparticle (PEG-AuNP) solutions. Induced by the addition of salts (i.e., Cs2SO4) to PEG-AuNPs solutions, two-dimensional hexagonal lattices of PEG-AuNPs form spontaneously at the aqueous surfaces, as is demonstrated by x-ray reflectivity and grazing incidence small-angle x-ray 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 PEG-AuNP film compared with that ...


Nonequilibrium Polarization Dynamics In Antiferroelectrics, M. M. Vopson, Xiaoli Tan 2018 University of Portsmouth

Nonequilibrium Polarization Dynamics In Antiferroelectrics, M. M. Vopson, Xiaoli Tan

Xiaoli Tan

A nonequilibrium statistical domain nucleation model of polarization dynamics in less understood antiferroelectric systems is introduced. Predictions of the model have been successfully tested experimentally using an antiferroelectric Pb0.99Nb0.02[( Zr0.57Sn0.43) Ti-0.94(0.06)] O-0.98(3) polycrystalline ceramic. We determined the activation energy of the domain nucleation process for this particular antiferroelectric sample to be W-b = 1.07 eV and the critical volume of the polar nucleus V * = 98 x 10(-27)m(3), which corresponds to a linear length scale of 2.86 nm.


Superelasticity And Cryogenic Linear Shape Memory Effects Of Cafe2as2, John T. Sypek, Hang Yu, Keith J. Dusoe, Gil Drachuck, Hetal Patel, Amanda M. Giroux, Alan I. Goldman, Andreas Kreyssig, Paul C. Canfield, Serguei L. Bud’ko, Christopher R. Weinberger, Seok-Woo Lee 2018 University of Connecticut

Superelasticity And Cryogenic Linear Shape Memory Effects Of Cafe2as2, John T. Sypek, Hang Yu, Keith J. Dusoe, Gil Drachuck, Hetal Patel, Amanda M. Giroux, Alan I. Goldman, Andreas Kreyssig, Paul C. Canfield, Serguei L. Bud’Ko, Christopher R. Weinberger, Seok-Woo Lee

Paul C. Canfield

Shape memory materials have the ability to recover their original shape after a significant amount of deformation when they are subjected to certain stimuli, for instance, heat or magnetic fields. However, their performance is often limited by the energetics and geometry of the martensitic-austenitic phase transformation. Here, we report a unique shape memory behavior in CaFe2As2, which exhibits superelasticity with over 13% recoverable strain, over 3 GPa yield strength, repeatable stress–strain response even at the micrometer scale, and cryogenic linear shape memory effects near 50 K. These properties are acheived through a reversible uni-axial phase transformation mechanism, the tetragonal ...


Vortex Creep At Very Low Temperatures In Single Crystals Of The Extreme Type-Ii Superconductor Rh9in4s4, Edwin Herrera, José Benito-Llorens, Udhara S. Kaluarachchi, Serguei Bud'ko, Paul C. Canfield, Isabel Guillamón, Hermann Suderow 2018 Universidad Autónoma de Madrid

Vortex Creep At Very Low Temperatures In Single Crystals Of The Extreme Type-Ii Superconductor Rh9in4s4, Edwin Herrera, José Benito-Llorens, Udhara S. Kaluarachchi, Serguei Bud'ko, Paul C. Canfield, Isabel Guillamón, Hermann Suderow

Paul C. Canfield

We image vortex creep at very low temperatures using scanning tunneling microscopy in the superconductor Rh9In4S4 (Tc=2.25K). We measure the superconducting gap of Rh9In4S4, finding Δ≈0.33meV, and image a hexagonal vortex lattice up to close to Hc2, observing slow vortex creep at temperatures as low as 150 mK. We estimate thermal and quantum barriers for vortex motion and show that thermal fluctuations likely cause vortex creep, in spite of being at temperatures T/Tc


Pressure Induced Half-Collapsed-Tetragonal Phase In Cakfe4as4, Udhara Kaluarachchi, Valentin Taufour, Aashish Sapkota, Vladislav Borisov, Tai Kong, W. R. Meier, Karunakar Kothapalli, Benjamin G. Ueland, Andreas Kreyssig, Roser Valenti, Robert J. McQueeney, Alan I. Goldman, Sergey L. Bud'ko, Paul C. Canfield 2018 Iowa State University and Ames Laboratory

Pressure Induced Half-Collapsed-Tetragonal Phase In Cakfe4as4, Udhara Kaluarachchi, Valentin Taufour, Aashish Sapkota, Vladislav Borisov, Tai Kong, W. R. Meier, Karunakar Kothapalli, Benjamin G. Ueland, Andreas Kreyssig, Roser Valenti, Robert J. Mcqueeney, Alan I. Goldman, Sergey L. Bud'ko, Paul C. Canfield

Paul C. Canfield

We report the temperature-pressure phase diagram of CaKFe4As4 established using high-pressure electrical resistivity, magnetization, and high-energy x-ray diffraction measurements up to 6 GPa. With increasing pressure, both resistivity and magnetization data show that the bulk superconducting transition of CaKFe4As4 is suppressed and then disappears at p≳4 GPa. High-pressure x-ray data clearly indicate a phase transition to a collapsed tetragonal phase in CaKFe4As4 under pressure that coincides with the abrupt loss of bulk superconductivity near 4 GPa. The x-ray data, combined with resistivity data, indicate that the collapsed tetragonal transition line is essentially independent of pressure, occurring at 4.0 ...


Nmr Study Of The New Magnetic Superconductor Cak ( Fe 0.951 Ni 0.049 ) 4 As 4 : Microscopic Coexistence Of The Hedgehog Spin-Vortex Crystal And Superconductivity, Qing-Ping Ding, William R. Meier, A. E. Böhmer, S. L. Bud’ko, Paul C. Canfield, Yuji Furukawa 2018 Iowa State University and Ames Laboratory

Nmr Study Of The New Magnetic Superconductor Cak ( Fe 0.951 Ni 0.049 ) 4 As 4 : Microscopic Coexistence Of The Hedgehog Spin-Vortex Crystal And Superconductivity, Qing-Ping Ding, William R. Meier, A. E. Böhmer, S. L. Bud’Ko, Paul C. Canfield, Yuji Furukawa

Paul C. Canfield

The coexistence of a new-type antiferromagnetic (AFM) state, the so-called hedgehog spin-vortex crystal (SVC), and superconductivity (SC) is evidenced by an 75 As nuclear magnetic resonance study on single-crystalline 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 spin-lattice relaxation rate 1 / T 1 shows a distinct decrease ...


Dirac Node Arcs In Ptsn4, Yun Wu, Lin-Lin Wang, Eundeok Mun, Duane D. Johnson, Daixiang Mou, Lunan Huang, Youngbin Lee, Serguei L. Bud’ko, Paul C. Canfield, Adam Kaminski 2018 Iowa State University and Ames Laboratory

Dirac Node Arcs In Ptsn4, Yun Wu, Lin-Lin Wang, Eundeok Mun, Duane D. Johnson, Daixiang Mou, Lunan Huang, Youngbin Lee, Serguei L. Bud’Ko, Paul C. Canfield, Adam Kaminski

Paul C. Canfield

In topological quantum materials1–3 the conduction and valence bands are connected at points or along lines in the momentum space. A number of studies have demonstrated that several materials are indeed Dirac/Weyl semimetals4–8 . However, there is still no experimental confirmation of materials with line nodes, in which the Dirac nodes form closed loops in the momentum space2,3 . Here we report the discovery of a novel topological structure—Dirac node arcs—in the ultrahigh magnetoresistive material PtSn4 using laser-based angle-resolved photoemission spectroscopy data and density functional theory calculations. Unlike the closed loops of line nodes, the Dirac ...


Extremely Large Magnetoresistance And Kohler's Rule In Pdsn4 : A Complete Study Of Thermodynamic, Transport, And Band-Structure Properties, Na Hyan Jo, Yun Wu, Lin-Lin Wang, Peter Orth, Savannah S. Downing, Soham Manni, Dixiang Mou, Duane D. Johnson, Adam Kaminski, Sergey L. Bud’ko, Paul C. Canfield 2018 Iowa State University and Ames Laboratory

Extremely Large Magnetoresistance And Kohler's Rule In Pdsn4 : A Complete Study Of Thermodynamic, Transport, And Band-Structure Properties, Na Hyan Jo, Yun Wu, Lin-Lin Wang, Peter Orth, Savannah S. Downing, Soham Manni, Dixiang Mou, Duane D. Johnson, Adam Kaminski, Sergey L. Bud’Ko, Paul C. Canfield

Paul C. Canfield

The recently discovered material PtSn4 is known to exhibit extremely large magnetoresistance (XMR) that also manifests Dirac arc nodes on the surface. PdSn4 is isostructural to PtSn4 with the same electron count. We report on the physical properties of high-quality single crystals of PdSn4 including specific heat, temperature- and magnetic-field-dependent resistivity and magnetization, and electronic band-structure properties obtained from angle-resolved photoemission spectroscopy (ARPES). We observe that PdSn4 has physical properties that are qualitatively similar to those of PtSn4, but find also pronounced differences. Importantly, the Dirac arc node surface state of PtSn4 is gapped out for PdSn4. By comparing these ...


Nmr Evidence For Static Local Nematicity And Its Cooperative Interplay With Low-Energy Magnetic Fluctuations In Fese Under Pressure, Paul W. Wiecki, A. E. Böhmer, Serguei L. Bud’ko, Paul C. Canfield, Yuji Furukawa 2018 Iowa State University and Ames Laboratory

Nmr Evidence For Static Local Nematicity And Its Cooperative Interplay With Low-Energy Magnetic Fluctuations In Fese Under Pressure, Paul W. Wiecki, A. E. Böhmer, Serguei L. Bud’Ko, Paul C. Canfield, Yuji Furukawa

Paul C. Canfield

We present 77Se -NMR measurements on single-crystalline 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 low-energy stripe-type antiferromagnetic spin fluctuations, as revealed by NMR spin-lattice 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.


Extremely Large Magnetoresistance And Kohler's Rule In Pdsn4 : A Complete Study Of Thermodynamic, Transport, And Band-Structure Properties, Na Hyan Jo, Yun Wu, Lin-Lin Wang, Peter Orth, Savannah S. Downing, Soham Manni, Dixiang Mou, Duane D. Johnson, Adam Kaminski, Sergey L. Bud’ko, Paul C. Canfield 2018 Iowa State University and Ames Laboratory

Extremely Large Magnetoresistance And Kohler's Rule In Pdsn4 : A Complete Study Of Thermodynamic, Transport, And Band-Structure Properties, Na Hyan Jo, Yun Wu, Lin-Lin Wang, Peter Orth, Savannah S. Downing, Soham Manni, Dixiang Mou, Duane D. Johnson, Adam Kaminski, Sergey L. Bud’Ko, Paul C. Canfield

Duane D. Johnson

The recently discovered material PtSn4 is known to exhibit extremely large magnetoresistance (XMR) that also manifests Dirac arc nodes on the surface. PdSn4 is isostructural to PtSn4 with the same electron count. We report on the physical properties of high-quality single crystals of PdSn4 including specific heat, temperature- and magnetic-field-dependent resistivity and magnetization, and electronic band-structure properties obtained from angle-resolved photoemission spectroscopy (ARPES). We observe that PdSn4 has physical properties that are qualitatively similar to those of PtSn4, but find also pronounced differences. Importantly, the Dirac arc node surface state of PtSn4 is gapped out for PdSn4. By comparing these ...


Antiferromagnetism In Semiconducting Srmn2sb2 And Bamn2sb2 Single Crystals, N. S. Sangeetha, V. Smetana, David C. Johnston 2018 Ames Laboratory

Antiferromagnetism In Semiconducting Srmn2sb2 And Bamn2sb2 Single Crystals, N. S. Sangeetha, V. Smetana, David C. Johnston

Ames Laboratory Accepted Manuscripts

Crystals of SrMn 2 Sb 2 and BaMn 2 Sb 2 were grown using Sn flux and characterized by powder and single-crystal x-ray diffraction, respectively, and by single-crystal electrical resistivity ρ , heat capacity C p , and magnetic susceptibility χ measurements versus temperature T , and magnetization versus field M ( H ) isotherm measurements. SrMn 2 Sb 2 adopts the trigonal CaAl 2 Si 2 -type structure, whereas BaMn 2 Sb 2 crystallizes in the tetragonal ThCr 2 Si 2 -type structure. The ρ ( T ) data indicate semiconducting behaviors for both compounds with activation energies of ≳ 0.35 eV for SrMn 2 Sb ...


Comparative Analysis Of Magnetic Resonance In The Polaron Pair Recombination And The Triplet Exciton-Polaron Quenching Models, Vagharsh Mkhitaryan, Dusan Danilovic, Chamika M. Hippola, M. E. Raikh, Joseph Shinar 2018 Ames Laboratory

Comparative Analysis Of Magnetic Resonance In The Polaron Pair Recombination And The Triplet Exciton-Polaron Quenching Models, Vagharsh Mkhitaryan, Dusan Danilovic, Chamika M. Hippola, M. E. Raikh, Joseph Shinar

Ames Laboratory Accepted Manuscripts

We present a comparative theoretical study of magnetic resonance within the polaron pair recombination (PPR) and the triplet exciton-polaron quenching (TPQ) models. Both models have been invoked to interpret the photoluminescence detected magnetic resonance (PLDMR) results in π -conjugated materials and devices. We show that resonance line shapes calculated within the two models differ dramatically in several regards. First, in the PPR model, the line shape exhibits unusual behavior upon increasing the microwave power: it evolves from fully positive at weak power to fully negative at strong power. In contrast, in the TPQ model, the PLDMR is completely positive, showing ...


Structural, Transport, And Topological Properties Induced At Complex-Oxide Hetero-Interfaces, Justin K. Thompson 2018 University of Kentucky

Structural, Transport, And Topological Properties Induced At Complex-Oxide Hetero-Interfaces, Justin K. Thompson

Theses and Dissertations--Physics and Astronomy

Complex-oxides have seen an enormous amount of attention in the realm of Condensed Matter Physics and Materials Science/Engineering over the last several decades. Their ability to host a wide variety of novel physical properties has even caused them to be exploited commercially as dielectric, metallic and magnetic materials. Indeed, since the discovery of high temperature superconductivity in the “Cuprates” in the late 1980’s there has been an explosion of activity involving complex-oxides. Further, as the experimental techniques and equipment for fabricating thin films and heterostructures of these materials has improved over the last several decades, the search for ...


Emergent Ising Degrees Of Freedom Above A Double-Stripe Magnetic Ground State, Guanghua Zhang, Rebecca Flint 2017 Iowa State University and Ames Laboratory

Emergent Ising Degrees Of Freedom Above A Double-Stripe Magnetic Ground State, Guanghua Zhang, Rebecca Flint

Ames Laboratory Accepted Manuscripts

Double-stripe magnetism [ Q = ( π / 2 , π / 2 ) ] has been proposed as the magnetic ground state for both the iron-telluride and BaTi 2 Sb 2 O families of superconductors. Double-stripe 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 spin-rotational symmetry, the ground-state 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 ...


Influence Of Classical Anisotropy Fields On The Properties Of Heisenberg Antiferromagnets Within Unified Molecular Field Theory, David C. Johnston 2017 Iowa State University and Ames Laboratory

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 crystallographically-equivalent 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 field-induced thermal-average 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 ...


Diffusion Of Two-Dimensional Epitaxial Clusters On Metal (100) Surfaces: Facile Versus Nucleation-Mediated Behavior And Their Merging For Larger Sizes, King C. Lai, Da-Jiang Liu, James W. Evans 2017 Iowa State University and Ames Laboratory

Diffusion Of Two-Dimensional Epitaxial Clusters On Metal (100) Surfaces: Facile Versus Nucleation-Mediated Behavior And Their Merging For Larger Sizes, King C. Lai, Da-Jiang Liu, James W. Evans

Ames Laboratory Accepted Manuscripts

For diffusion of two-dimensional 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 nucleation-mediated diffusion with small β<1 for “perfect” sizes N=Np=L2 or L(L+1), for L=3,4, ... having unique ground-state 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 lattice-gas 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 ground-state and low-lying excited state cluster configurations, and also of kink populations.


Ionic Depletion At The Crystalline Gibbs Layer Of Peg-Capped Gold Nanoparticle Brushes At Aqueous Surfaces, Wenjie Wang, Honghu Zhang, Surya Mallapragada, Alex Travesset, David Vaknin 2017 Ames Laboratory

Ionic Depletion At The Crystalline Gibbs Layer Of Peg-Capped Gold Nanoparticle Brushes At Aqueous Surfaces, Wenjie Wang, Honghu Zhang, Surya Mallapragada, Alex Travesset, David Vaknin

Ames Laboratory Accepted Manuscripts

In situ surface-sensitive x-ray diffraction and grazing incidence x-ray fluorescence spectroscopy (GIXFS) methods are combined to determine the ionic distributions across the liquid/vapor interfaces of thiolated-polyethylene-glycol–capped gold nanoparticle (PEG-AuNP) solutions. Induced by the addition of salts (i.e., Cs2SO4) to PEG-AuNPs solutions, two-dimensional hexagonal lattices of PEG-AuNPs form spontaneously at the aqueous surfaces, as is demonstrated by x-ray reflectivity and grazing incidence small-angle x-ray 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 PEG-AuNP film compared with that ...


Generalized Ellipsometry On Complex Nanostructures And Low-Symmetry Materials, Alyssa Mock 2017 University of Nebraska-Lincoln

Generalized Ellipsometry On Complex Nanostructures And Low-Symmetry Materials, Alyssa Mock

Theses, Dissertations, and Student Research from Electrical & Computer Engineering

In this thesis, complex anisotropic materials are investigated and characterized by generalized ellipsometry. In recent years, anisotropic materials have gained considerable interest for novel applications in electronic and optoelectronic devices, mostly due to unique properties that originate from reduced crystal symmetry. Examples include white solid-state lighting devices which have become ubiquitous just recently, and the emergence of high-power, high-voltage electronic transistors and switches in all-electric vehicles. The incorporation of single crystalline material with low crystal symmetry into novel device structures requires reconsideration of existing optical characterization approaches. Here, the generalized ellipsometry concept is extended to include applications for materials with ...


Nmr Study Of The New Magnetic Superconductor Cak ( Fe 0.951 Ni 0.049 ) 4 As 4 : Microscopic Coexistence Of The Hedgehog Spin-Vortex Crystal And Superconductivity, Qing-Ping Ding, William R. Meier, A. E. Böhmer, S. L. Bud’ko, Paul C. Canfield, Yuji Furukawa 2017 Iowa State University and Ames Laboratory

Nmr Study Of The New Magnetic Superconductor Cak ( Fe 0.951 Ni 0.049 ) 4 As 4 : Microscopic Coexistence Of The Hedgehog Spin-Vortex Crystal And Superconductivity, Qing-Ping Ding, William R. Meier, A. E. Böhmer, S. L. Bud’Ko, Paul C. Canfield, Yuji Furukawa

Ames Laboratory Accepted Manuscripts

The coexistence of a new-type antiferromagnetic (AFM) state, the so-called hedgehog spin-vortex crystal (SVC), and superconductivity (SC) is evidenced by an 75 As nuclear magnetic resonance study on single-crystalline 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 spin-lattice relaxation rate 1 / T 1 shows a distinct decrease ...


Emergent Bloch Excitations In Mott Matter, Nicola Lanatà, Tsung-Han Lee, Yong-Xin Yao, Vladimir Dobrosavljević 2017 Florida State University

Emergent Bloch Excitations In Mott Matter, Nicola Lanatà, Tsung-Han Lee, Yong-Xin 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 well-defined 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 ...


Digital Commons powered by bepress