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Articles 1 - 30 of 2607

Full-Text Articles in Physics

Fatigue-Resistant High-Performance Elastocaloric Materials Via Additive Manufacturing, Huilong Hou, Emrah Simsek, Tao Ma, Nathan S. Johnson, Suxin Qian, Cheikh Cissé, Drew Stasak, Naila Al Hasan, Lin Zhou, Yunho Hwang, Reinhard Radermacher, Valery I. Levitas, Matthew J. Kramer, Mohsen Asle Zaeem, Aaron P. Stebner, Ryan T. Ott, Jun Cui, Ichiro Takeuchi Aug 2019

Fatigue-Resistant High-Performance Elastocaloric Materials Via Additive Manufacturing, Huilong Hou, Emrah Simsek, Tao Ma, Nathan S. Johnson, Suxin Qian, Cheikh Cissé, Drew Stasak, Naila Al Hasan, Lin Zhou, Yunho Hwang, Reinhard Radermacher, Valery I. Levitas, Matthew J. Kramer, Mohsen Asle Zaeem, Aaron P. Stebner, Ryan T. Ott, Jun Cui, Ichiro Takeuchi

Aerospace Engineering Publications

Elastocaloric cooling, which exploits the latent heat released and absorbed as stress-induced phase transformations are reversibly cycled in shape memory alloys, has recently emerged as a frontrunner in non-vapor-compression cooling technologies. The intrinsically high thermodynamic efficiency of elastocaloric materials is limited only by work hysteresis. Here, we report on creating high-performance low-hysteresis elastocaloric cooling materials via additive manufacturing of Titanium-Nickel (Ti-Ni) alloys. Contrary to established knowledge of the physical metallurgy of Ti-Ni alloys, intermetallic phases are found to be beneficial to elastocaloric performances when they are combined with the binary Ti-Ni compound in nanocomposite configurations. The resulting microstructure gives rise ...


Self-Consistent Two-Gap Description Of Mgb2 Superconductor, Hyunsoo Kim, Kyuil Cho, Makariy A. Tanatar, Valentin Taufour, Stella K. Kim, Sergey L. Bud’Ko, Paul C. Canfield, Vladimir G. Kogan, Ruslan Prozorov Aug 2019

Self-Consistent Two-Gap Description Of Mgb2 Superconductor, Hyunsoo Kim, Kyuil Cho, Makariy A. Tanatar, Valentin Taufour, Stella K. Kim, Sergey L. Bud’Ko, Paul C. Canfield, Vladimir G. Kogan, Ruslan Prozorov

Ames Laboratory Accepted Manuscripts

A self-consistent two-gap γ -model is used to quantitatively describe several thermodynamic properties of MgB 2 superconductor. The superconducting coupling matrix, νij , was obtained from the fitting of the superfluid density in the entire superconducting temperature range. Using this input, temperature-dependent superconducting gaps, specific heat, and upper critical fields were calculated with no adjustable parameters and compared with the experimental data as well as with the first-principles calculations. The observed agreement between fit and data shows that γ -model provides adequate quantitative description of the two-gap superconductivity in MgB 2 and may serve as a relatively simple and versatile self-consistent ...


Hole Doping And Antiferromagnetic Correlations Above The Néel Temperature Of The Topological Semimetal (Sr1-X Kx) Mnsb2, Yong Liu, Farhan Islam, Kevin W. Dennis, Wei Tian, Benjamin G. Ueland, Robert J. Mcqueeney, David Vaknin Jul 2019

Hole Doping And Antiferromagnetic Correlations Above The Néel Temperature Of The Topological Semimetal (Sr1-X Kx) Mnsb2, Yong Liu, Farhan Islam, Kevin W. Dennis, Wei Tian, Benjamin G. Ueland, Robert J. Mcqueeney, David Vaknin

Ames Laboratory Accepted Manuscripts

Neutron diffraction and magnetic susceptibility studies of orthorhombic single crystal (Sr0.97K0.03)MnSb2 confirm the three-dimensional (3D) C-type antiferromagnetic (AFM) ordering of the Mn2+ moments at TN=305±3 K, which is slightly higher than that of the parent SrMnSb2 with TN=297±3 K. Susceptibility measurements of the K-doped and parent crystals above TN are characteristic of 2D AFM systems. This is consistent with high-temperature neutron diffraction of the parent compound that displays persisting 2D AFM correlations well above TN to at least ∼560 K with no evidence of a ferromagnetic phase. Analysis of the de Haas–van ...


Temperature-Dependent Anisotropies Of Upper Critical Field And London Penetration Depth, V. G. Kogan, Ruslan Prozorov, A. E. Koshelev Jul 2019

Temperature-Dependent Anisotropies Of Upper Critical Field And London Penetration Depth, V. G. Kogan, Ruslan Prozorov, A. E. Koshelev

Ames Laboratory Accepted Manuscripts

We show on a few examples of one-band materials with spheroidal Fermi surfaces and anisotropic order parameters that anisotropies γH of the upper critical field and γλ of the London penetration depth depend on temperature, a feature commonly attributed to multiband superconductors. The parameters γH and γλ may have opposite temperature dependences or may change in the same direction depending on the Fermi-surface shape and on the character of the gap nodes. For two-band systems, the behavior of anisotropies is affected by the ratios of bands densities of states, Fermi velocities, anisotropies, and order parameters. We investigate in detail the ...


Anisotropy And Orbital Moment In Sm-Co Permanent Magnets, Bhaskar Das, Renu Choudhary, Ralph Skomski, Balamurugan Balasubramanian, Arjun K. Pathak, Durga Paudyal, David J. Sellmyer Jul 2019

Anisotropy And Orbital Moment In Sm-Co Permanent Magnets, Bhaskar Das, Renu Choudhary, Ralph Skomski, Balamurugan Balasubramanian, Arjun K. Pathak, Durga Paudyal, David J. Sellmyer

Ames Laboratory Accepted Manuscripts

Structural and magnetic properties of iron-free and iron-substituted SmCo5 have been investigated theoretically and experimentally. The nanocrystalline ribbons of SmCo5−xFex(0≤x≤2), which were produced by rapid solidification, crystallize in the hexagonal CaCu5 structure for x≤0.75. Small Fe additions (x=0.25) substantially improve the coercivity, from 0.45 to 2.70 T, which we interpret as combined intrinsic and extrinsic effect. Most of our findings are consistent with past samarium-cobalt research, but some are at odds with findings that have seemingly been well established through decades of rare-earth transition-metal research. In particular, our local spin-density ...


Antiferromagnetic Stacking Of Ferromagnetic Layers And Doping-Controlled Phase Competition In Ca1−X Srx Co2−Y As2, Bing Li, Yuriy Sizyuk, Nediadath S. Sangeetha, John M. Wilde, Pinaki Das, W. Tian, David C. Johnston, Alan I. Goldman, Andreas Kreyssig, Peter P. Orth, Robert J. Mcqueeney, Benjamin G. Ueland Jul 2019

Antiferromagnetic Stacking Of Ferromagnetic Layers And Doping-Controlled Phase Competition In Ca1−X Srx Co2−Y As2, Bing Li, Yuriy Sizyuk, Nediadath S. Sangeetha, John M. Wilde, Pinaki Das, W. Tian, David C. Johnston, Alan I. Goldman, Andreas Kreyssig, Peter P. Orth, Robert J. Mcqueeney, Benjamin G. Ueland

Ames Laboratory Accepted Manuscripts

In search of a quantum phase transition between the two-dimensional (2D) ferromagnetism of CaCo2−yAs2 and stripe-type antiferromagnetism in SrCo2 As2, we instead find evidence for 1D magnetic frustration between magnetic square Co layers. We present neutron-diffraction data for Ca1−x Srx Co2−y As2 that reveal a sequence of x -dependent magnetic transitions which involve different stacking of 2 D ferromagnetically aligned layers with different magnetic anisotropy. We explain the x-dependent changes to the magnetic order by utilizing classical analytical calculations of a 1D Heisenberg model where single-ion magnetic anisotropy and frustration of antiferromagnetic nearest- and next-nearest-layer exchange interactions ...


Tuning Phase-Stability And Short-Range Order Through Ai-Doping In (Cocrfemn)100-Xaix High Entropy Alloys, Prashant Singh, Amalraj Marshal, A. V. Smirnov, Aayush Sharma, Ganesh Balasubramanian, K. G. Pradeep, Duane D. Johnson Jul 2019

Tuning Phase-Stability And Short-Range Order Through Ai-Doping In (Cocrfemn)100-Xaix High Entropy Alloys, Prashant Singh, Amalraj Marshal, A. V. Smirnov, Aayush Sharma, Ganesh Balasubramanian, K. G. Pradeep, Duane D. Johnson

Ames Laboratory Accepted Manuscripts

For (CoCrFeMn)100−xAlx high-entropy alloys, we investigate the phase evolution with increasing Al content (0≤x≤20 at.%). From first-principles theory, aluminum doping drives the alloy structurally from fcc to bcc separated by a narrow two-phase region (fcc+bcc), which is well supported by our experiments. Using KKR-CPA electronic-structure calculations, we highlight the effect of Al doping on the formation enthalpy (alloy stability) and electronic dispersion of (CoCrFeMn)100−xAlx alloys. As chemical short-range order indicates the nascent local order, and entropy changes, as well as expected low-temperature ordering behavior, we use KKR-CPA-based thermodynamic linear response to predict the ...


Interplay Between Superconductivity And Itinerant Magnetism In Underdoped Ba1−Xkxfe2as2 (X = 0.2) Probed By The Response To Controlled Point-Like Disorder, Ruslan Prozorov, Marcin Kończykowski, Makariy A. Tanatar, Hai-Hu Wen, Rafael M. Fernandes, Paul C. Canfield Jul 2019

Interplay Between Superconductivity And Itinerant Magnetism In Underdoped Ba1−Xkxfe2as2 (X = 0.2) Probed By The Response To Controlled Point-Like Disorder, Ruslan Prozorov, Marcin Kończykowski, Makariy A. Tanatar, Hai-Hu Wen, Rafael M. Fernandes, Paul C. Canfield

Ames Laboratory Accepted Manuscripts

The response of superconductors to controlled introduction of point-like disorder is an important tool to probe their microscopic electronic collective behavior. In the case of iron-based superconductors, magnetic fluctuations presumably play an important role in inducing high-temperature superconductivity. In some cases, these two seemingly incompatible orders coexist microscopically. Therefore, understanding how this unique coexistence state is affected by disorder can provide important information about the microscopic mechanisms involved. In one of the most studied pnictide family, hole-doped Ba1−xKxFe2As2 (BaK122), this coexistence occurs over a wide range of doping levels, 0.16 ≲ x ≲ 0.25. We used ...


Single Pair Of Weyl Fermions In The Half-Metallic Semimetal Eucd2as2, Lin-Lin Wang, Na Hyun Jo, Brinda Kuthanazhi, Yun Wu, Robert J. Mcqueeney, Adam Kaminski, Paul C. Canfield Jun 2019

Single Pair Of Weyl Fermions In The Half-Metallic Semimetal Eucd2as2, Lin-Lin Wang, Na Hyun Jo, Brinda Kuthanazhi, Yun Wu, Robert J. Mcqueeney, Adam Kaminski, Paul C. Canfield

Ames Laboratory Accepted Manuscripts

Materials with the ideal case of a single pair of Weyl points (WPs) are highly desirable for elucidating the unique properties of Weyl fermions. EuC d 2 A s 2 is an antiferromagnetic topological insulator or Dirac semimetal depending on the different magnetic configurations. Using first-principles band-structure calculations, we show that inducing ferromagnetism in EuC d 2 A s 2 can generate a single pair of WPs from splitting the single pair of antiferromagnetic Dirac points due to its half-metallic nature. Analysis with a low-energy effective Hamiltonian shows that a single pair of WPs is obtained in EuC d 2 ...


Magnetic Structure And Magnetization Of Z -Axis Helical Heisenberg Antiferromagnets With Xy Anisotropy In High Magnetic Fields Transverse To The Helix Axis At Zero Temperature, David C. Johnston Jun 2019

Magnetic Structure And Magnetization Of Z -Axis Helical Heisenberg Antiferromagnets With Xy Anisotropy In High Magnetic Fields Transverse To The Helix Axis At Zero Temperature, David C. Johnston

Ames Laboratory Accepted Manuscripts

A helix has a wave vector along the z axis with the magnetic moments ferromagnetically aligned within xy planes with a turn angle kd between the moments in adjacent planes in transverse field H=Hxˆi=0. The magnetic structure and x-axis average magnetization per spin of this system in a classical XY anisotropy field HA is studied versus kd, HA, and large Hx at zero temperature. For values of HA below a kd-dependent maximum value, the xy helix phase transitions with increasing Hx into a spin-flop (SF) phase where the ordered moments have x, y, and z components. The moments ...


Two-Dimensional Ordering And Collective Magnetic Excitations In The Dilute Ferromagnetic Topological Insulator (Bi0.95 Mn0.05)2 Te3, David Vaknin, Daniel M. Pajerowski, Deborah L. Schlagel, Kevin W. Dennis, Robert Mcqueeney Jun 2019

Two-Dimensional Ordering And Collective Magnetic Excitations In The Dilute Ferromagnetic Topological Insulator (Bi0.95 Mn0.05)2 Te3, David Vaknin, Daniel M. Pajerowski, Deborah L. Schlagel, Kevin W. Dennis, Robert Mcqueeney

Ames Laboratory Accepted Manuscripts

Employing elastic and inelastic neutron scattering (INS) techniques, we report on the microscopic properties of the ferromagnetism in the dilute magnetic topological insulator (Bi0.95Mn0.05)2 Te3. Neutron diffraction of polycrystalline samples shows the ferromagnetic (FM) ordering is long range within the basal plane, and mainly two dimensional (2D) in character with short-range correlations between layers below T C ≈ 13 K. Remarkably, we observe gapped and collective magnetic excitations in this dilute magnetic system. The excitations appear typical of quasi-2D FM systems despite the severe broadening of short-wavelength magnons which is expected from the random spatial distribution of Mn ...


Interaction Dynamics Between Ferroelectric And Antiferroelectric Domains In A Pbzro3-Based Ceramic, Zhongming Fan, Fei Xue, Goknur Tutuncu, Long-Qing Chen, Xiaoli Tan Jun 2019

Interaction Dynamics Between Ferroelectric And Antiferroelectric Domains In A Pbzro3-Based Ceramic, Zhongming Fan, Fei Xue, Goknur Tutuncu, Long-Qing Chen, Xiaoli Tan

Materials Science and Engineering Publications

The antiferroelectric-ferroelectric phase transition in PbZrO3-based oxides is of both fundamental and practical importance. In ceramics in which such a transition readily occurs, the antiferroelectric and the ferroelectric phases often coexist in individual grains with a coherent interphase interface. In this work, the electric biasing in situ transmission electron microscopy technique is employed to directly observe a unique microstructural dynamic when ferroelectric and antiferroelectric domains are driven by a moderate electric field to interact. It is found that, under monotonic loading, the ferroelectric domain grows until it is blocked by the ferroelectric-antiferroelectric interface. At the same time, a kink is ...


Ultrahigh Elastically Compressible And Strain-Engineerable Intermetallic Compounds Under Uniaxial Mechanical Loading, Gyuho Song, Vladislav Borisov, William Meier, Mingyu Xu, Keith J. Dusoe, John T. Sypek, Roser Valentí, Paul C. Canfield, Seok-Woo Lee Jun 2019

Ultrahigh Elastically Compressible And Strain-Engineerable Intermetallic Compounds Under Uniaxial Mechanical Loading, Gyuho Song, Vladislav Borisov, William Meier, Mingyu Xu, Keith J. Dusoe, John T. Sypek, Roser Valentí, Paul C. Canfield, Seok-Woo Lee

Ames Laboratory Accepted Manuscripts

Intermetallic compounds possess unique atomic arrangements that often lead to exceptional material properties, but their extreme brittleness usually causes fracture at a limited strain of less than 1% and prevents their practical use. Therefore, it is critical for them to exhibit either plasticity or some form of structural transition to absorb and release a sufficient amount of mechanical energy before failure occurs. This study reports that the ThCr2Si2-structured intermetallic compound (CaFe2As2) and a hybrid of its structure (CaKFe4As4) with 2 µm in diameter and 6 µm in height can exhibit superelasticity with strain up to 17% through a reversible, deformation-induced ...


Topological States In A15 Superconductors, Minsung Kim, Cai-Zhuang Wang, Kai-Ming Ho Jun 2019

Topological States In A15 Superconductors, Minsung Kim, Cai-Zhuang Wang, Kai-Ming Ho

Ames Laboratory Accepted Manuscripts

Superconductors with the A15 structure are prototypical type-II s-wave superconductors which have generated considerable interest in early superconducting material history. However, the topological nature of the electronic structure remains unnoticed so far. Here, using first-principles band structure calculations based on density-functional theory, we show that the A15 superconductors (Ta3Sb, Ta3Sn, and Ta3Pb) have nontrivial band topology in the bulk electronic band structures, leading to the formation of topological surface states near the Fermi energy. Due to the bulk superconductivity, the proximity effect in the topological surface states would induce topological superconductivity even without heterostructure of a topological insulator and an ...


A Quadrature-Based Moment Method For Polydisperse Bubbly Flows, Jeffrey C. Heylmun, Bo Kong, Alberto Passalacqua, Rodney O. Fox Jun 2019

A Quadrature-Based Moment Method For Polydisperse Bubbly Flows, Jeffrey C. Heylmun, Bo Kong, Alberto Passalacqua, Rodney O. Fox

Chemical and Biological Engineering Publications

A computational algorithm for polydisperse bubbly flow is developed by combining quadrature-based moment methods (QBMM) with an existing two-fluid solver for gas–liquid flows. Care is taken to ensure that the two-fluid model equations are hyperbolic by generalizing the kinetic model for the bubble phase proposed by Bieseuvel and Gorissen (1990). The kinetic formulation for the bubble phase includes the full suite of interphase momentum exchange terms for bubbly flow, as well as ad hoc bubble–bubble interaction terms to model the transition from isolated bubbles to regions of pure air at very high bubble-phase volume fractions. A robust numerical ...


Magnetic Fluctuations In The Itinerant Ferromagnet Lacrge3 Studied By 139la Nmr, K. Rana, H. Kotegawa, R. R. Ullah, J. S. Harvey, Sergey L. Bud’Ko, Paul C. Canfield, H. Tou, V. Taufour, Yuji Furukawa Jun 2019

Magnetic Fluctuations In The Itinerant Ferromagnet Lacrge3 Studied By 139la Nmr, K. Rana, H. Kotegawa, R. R. Ullah, J. S. Harvey, Sergey L. Bud’Ko, Paul C. Canfield, H. Tou, V. Taufour, Yuji Furukawa

Ames Laboratory Accepted Manuscripts

LaCrGe3 is an itinerant ferromagnet with a Curie temperature of T C = 85 K and exhibits an avoided ferromagnetic quantum critical point under pressure through a modulated antiferromagnetic phase as well as tricritical wing structure in its temperature-pressure-magnetic field ( T – p – H) phase diagram. In order to understand the static and dynamical magnetic properties of LaCrGe3 , we carried out 139 La nuclear magnetic resonance (NMR) measurements. Based on the analysis of NMR data, using the self-consistent-renormalization (SCR) theory, the spin fluctuations in the paramagnetic state are revealed to be isotropic ferromagnetic and three dimensional (3D) in nature. Furthermore, the system ...


Crystal Growth And Magnetic Structure Of Mnbi2 Te 4, J.-Q. Yan, Q. Zhang, T. Heitmann, Zengle Huang, K. Y. Chen, J.-G. Cheng, Weida Wu, David Vaknin, B. C. Sales, Robert J. Mcqueeney Jun 2019

Crystal Growth And Magnetic Structure Of Mnbi2 Te 4, J.-Q. Yan, Q. Zhang, T. Heitmann, Zengle Huang, K. Y. Chen, J.-G. Cheng, Weida Wu, David Vaknin, B. C. Sales, Robert J. Mcqueeney

Ames Laboratory Accepted Manuscripts

Millimeter-sized MnBi2Te4 single crystals are grown out of a Bi-Te flux and characterized using magnetic, transport, scanning tunneling microscopy, and spectroscopy measurements. The magnetic structure of MnBi2Te4 below TN is determined by powder and single-crystal neutron diffraction measurements. Below TN = 24 K, Mn2+ moments order ferromagnetically in the ab plane but antiferromagnetically along the crystallographic c axis. The ordered moment is 4.04(13)μB/Mn at 10 K and aligned along the crystallographic c axis in an A-type antiferromagnetic order. Below TN, the electrical resistivity drops upon cooling or when going across the metamagnetic transition in increasing magnetic fields ...


Thermodynamic Stabilities Of Perfect And Vacancy-Defected Li2 Tio3 (001) Surfaces From First-Principles Analyses, Yan Jiang, Yanli Shi, Xiaogang Xiang, Jianqi Qi, Yong Han, Zhijun Liao, Tiecheng Lu May 2019

Thermodynamic Stabilities Of Perfect And Vacancy-Defected Li2 Tio3 (001) Surfaces From First-Principles Analyses, Yan Jiang, Yanli Shi, Xiaogang Xiang, Jianqi Qi, Yong Han, Zhijun Liao, Tiecheng Lu

Ames Laboratory Accepted Manuscripts

Lithium titanate (Li2TiO3) is an attractive ceramic material for various industrial applications, particularly as one of the most promising breeder blanket materials in future nuclear-fusion reactors. Previously reported studies mainly focus on sintered polycrystalline samples of Li2TiO3. Surface structure of the single-crystal form is rarely reported, although the information of surface structures and stabilities can be critical for further understanding the surface-associated processes. In this work, we perform extensive first-principles density-functional-theory (DFT) calculations to obtain the surface energies of Li2TiO3 (001) with different surface terminations. For four perfect (defect-free) Li-, O-, or LiTi-terminated (001) surfaces, Li- or O-terminated (001) surfaces ...


Magnetic-Field Effects On The Fragile Antiferromagnetism In Ybbipt, Benjamin G. Ueland, Andreas Kreyssig, E. D. Mun, J. W. Lynn, L. W. Harriger, D. K. Pratt, K. Prokeš, Z. Hüsges, R. Toft-Petersen, S. Sauerbrei, Scott M. Saunders, Yuji Furukawa, Sergey L. Bud’Ko, Robert J. Mcqueeney, Paul C. Canfield, Alan I. Goldman May 2019

Magnetic-Field Effects On The Fragile Antiferromagnetism In Ybbipt, Benjamin G. Ueland, Andreas Kreyssig, E. D. Mun, J. W. Lynn, L. W. Harriger, D. K. Pratt, K. Prokeš, Z. Hüsges, R. Toft-Petersen, S. Sauerbrei, Scott M. Saunders, Yuji Furukawa, Sergey L. Bud’Ko, Robert J. Mcqueeney, Paul C. Canfield, Alan I. Goldman

Ames Laboratory Accepted Manuscripts

We present neutron-diffraction data for the cubic-heavy-fermion YbBiPt that show broad magnetic diffraction peaks due to the fragile short-range antiferromagnetic (AFM) order persist under an applied magnetic-field H. Our results for H perpendicular to[(1) over bar 1 0] and a temperature of T = 0.14(1) K show that the (1/2,1/2,3/2) magnetic diffraction peak can be described by the same two-peak line shape found for mu H-0 = 0T below the Neel temperature of T-N = 0.4 K. Both components of the peak exist for mu H-0 less than or similar to 1.4 T ...


Characteristics Of Sulfur Atoms Adsorbed On Ag(100), Ag(110), And Ag(111) As Probed With Scanning Tunneling Microscopy: Experiment And Theory, Peter M. Spurgeon, Da-Jiang Liu, Holly Walen, Junepyo Oh, Hyun Jin Yang, Yousoo Kim, Patricia A. Thiel May 2019

Characteristics Of Sulfur Atoms Adsorbed On Ag(100), Ag(110), And Ag(111) As Probed With Scanning Tunneling Microscopy: Experiment And Theory, Peter M. Spurgeon, Da-Jiang Liu, Holly Walen, Junepyo Oh, Hyun Jin Yang, Yousoo Kim, Patricia A. Thiel

Chemistry Publications

In this paper, we report that S atoms on Ag(100) and Ag(110) exhibit a distinctive range of appearances in scanning tunneling microscopy (STM) images, depending on the sample bias voltage, VS. Progressing from negative to positive VS, the atomic shape can be described as a round protrusion surrounded by a dark halo (sombrero) in which the central protrusion shrinks, leaving only a round depression. This progression resembles that reported previously for S atoms on Cu(100). We test whether DFT can reproduce these shapes and the transition between them, using a modified version of the Lang–Tersoff–Hamann ...


Measurement Of Charm And Bottom Production From Semileptonic Hadron Decays In P + P Collisions At √S = 200 Gev, C. Aidala, Nicole J. Apadula, John C. Hill, Nels J. Hotvedt, 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, M. Shimomura, Arbin Timilsina, Yunxiao Zhai, Et Al., Phenix Collaboration May 2019

Measurement Of Charm And Bottom Production From Semileptonic Hadron Decays In P + P Collisions At √S = 200 Gev, C. Aidala, Nicole J. Apadula, John C. Hill, Nels J. Hotvedt, 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, M. Shimomura, Arbin Timilsina, Yunxiao Zhai, Et Al., Phenix Collaboration

Physics and Astronomy Publications

Measurements of the differential production of electrons from open-heavy-flavor hadrons with charm- and bottom-quark content in p+p collisions at √s=200  GeV are presented. The measurements proceed through displaced-vertex analyses of electron tracks from the semileptonic decay of charm and bottom hadrons using the PHENIX silicon-vertex detector. The relative contribution of electrons from bottom decays to inclusive heavy-flavor-electron production is found to be consistent with fixed-order-plus-next-to-leading-log perturbative-QCD calculations within experimental and theoretical uncertainties. These new measurements in p+p collisions provide a precision baseline for comparable forthcoming measurements in A+A collisions.


Measurement Of Two-Particle Correlations With Respect To Second- And Third-Order Event Planes In Au + Au Collisions At √Snn=200 Gev, A. Adare, John C. Hill, Nels J. Hotvedt, Todd Kempel, John G. Lajoie, Alexandre Lebedev, S. H. Lee, Craig Ogilvie, Milap R. Patel, H. Pei, Timothy T. Rinn, Marzia Rosati, Jonathan C. Runchey, Alexey Yu. Semenov, M. Shimomura, Carla Vale, Feng Wei, Et Al., Phenix Collaboration May 2019

Measurement Of Two-Particle Correlations With Respect To Second- And Third-Order Event Planes In Au + Au Collisions At √Snn=200 Gev, A. Adare, John C. Hill, Nels J. Hotvedt, Todd Kempel, John G. Lajoie, Alexandre Lebedev, S. H. Lee, Craig Ogilvie, Milap R. Patel, H. Pei, Timothy T. Rinn, Marzia Rosati, Jonathan C. Runchey, Alexey Yu. Semenov, M. Shimomura, Carla Vale, Feng Wei, Et Al., Phenix Collaboration

Physics and Astronomy Publications

We present measurements of azimuthal correlations of charged hadron pairs in root s(NN) = 200 GeV Au + Au collisions for the trigger and associated particle transverse-momentum ranges of 1 < p(T)(t) < 10 GeV/c and 0.5 < p(T)(a) < 10 GeV/c. After subtraction of an underlying event using a model that includes higher-order azimuthal anisotropy v(2), v(3,) and v(4), the away-side yield of the highest trigger-p(T)(p(T)(t) > 4 GeV/c) correlations is suppressed compared with that of correlations measured in p + p collisions. At the lowest associated particle p(T)(0.5 < p(T)(a) < 1 GeV/c), the away-side shape and yield are modified relative to those in p + p collisions. These observations are consistent with the scenario of radiative-jet energy loss. For the low-p(T) trigger correlations (2 < p(T)(t) < 4 GeV/c), a finite away-side yield exists and we explore the dependence of the shape of the away-side within the context of an underlying-event model. Correlations are also studied differentially versus event-plane angle Psi(2) and Psi(3). The angular correlations show an asymmetry when selecting the sign of the difference between the trigger-particle azimuthal angle and the Psi(2) event plane. This asymmetry and the measured suppression of the pair yield out-of-plane is consistent with a path-length-dependent energy loss. No Psi(3) dependence can be resolved within experimental uncertainties.


Observation Of Η-Al41sm5 Reveals Motif-Aware Structural Evolution In Al-Sm Alloys, Zhuo Ye, F. Meng, Feng Zhang, Yang Sun, L. Yang, S. H. Zhou, Ralph E. Napolitano, Mikhail I. Mendelev, Ryan T. Ott, Matthew J. Kramer, Cai-Zhuang Wang, Kai-Ming Ho Apr 2019

Observation Of Η-Al41sm5 Reveals Motif-Aware Structural Evolution In Al-Sm Alloys, Zhuo Ye, F. Meng, Feng Zhang, Yang Sun, L. Yang, S. H. Zhou, Ralph E. Napolitano, Mikhail I. Mendelev, Ryan T. Ott, Matthew J. Kramer, Cai-Zhuang Wang, Kai-Ming Ho

Materials Science and Engineering Publications

Using an effective genetic algorithm, we uncover the structure of a metastable Al41Sm5 phase that supplements its family sharing similar short-range orders. The phase evolves upon heating an amorphous Al-9.7 at.% Sm ribbon, produced by melt-spinning. The dynamical phase selection is discussed with respect to the structural connections between the short-range packing motifs in the amorphous precursor and those observed in the selected phases. The phase elucidated here is one of several newly discovered large-unit-cell phases found to form during devitrification from the glass in this binary system, further illustrating the power and efficiency of our approach, the important ...


Magnetocaloric Effect Of Gadolinium In High Magnetic Fields, T. Gottschall, M. D. Kuz’Min, K. P. Skokov, Y. Skourski, M. Fries, O. Gutfleisch, M. Ghorbani Zavareh, Deborah L. Schlagel, Yaroslav Mudryk, Vitalij K. Pecharsky, J. Wosnitza Apr 2019

Magnetocaloric Effect Of Gadolinium In High Magnetic Fields, T. Gottschall, M. D. Kuz’Min, K. P. Skokov, Y. Skourski, M. Fries, O. Gutfleisch, M. Ghorbani Zavareh, Deborah L. Schlagel, Yaroslav Mudryk, Vitalij K. Pecharsky, J. Wosnitza

Ames Laboratory Accepted Manuscripts

The magnetocaloric effect of gadolinium has been measured directly in pulsed magnetic fields up to 62 T. The maximum observed adiabatic temperature change is Delta T-ad = 60.5 K, the initial temperature T-0 being just above 300 K. The field dependence of Delta T-ad is found to follow the usual H-2/3 law, with a small correction in H-4/3. However, as H is increased, a radical change is observed in the dependence of Delta T-ad on T-0, at H = const. The familiar caret-shaped peak situated at T-0 = T-C becomes distinctly asymmetric, its high-temperature slope becoming more gentle and evolving ...


Anisotropy Induced Vortex Lattice Rearrangement In Cakfe4as4, Rustem Khasanov, William R. Meier, Sergey L. Bud’Ko, Hubertus Luetkens, Paul C. Canfield, Alex Amato Apr 2019

Anisotropy Induced Vortex Lattice Rearrangement In Cakfe4as4, Rustem Khasanov, William R. Meier, Sergey L. Bud’Ko, Hubertus Luetkens, Paul C. Canfield, Alex Amato

Ames Laboratory Accepted Manuscripts

The magnetic penetration depth anisotropy gamma(lambda) = lambda(c)/lambda(ab) (lambda(ab) and lambda(c) are the in-plane and the out-of-plane components of the magnetic penetration depth) in a CaKFe4As4 single crystal sample (the critical temperature T-c similar or equal to 35 K) was studied by means of muon-spin rotation (mu SR). gamma(lambda) is almost temperature independent for T less than or similar to 20 K (gamma(lambda) similar or equal to 1.9) and it reaches similar or equal to 3.0 by approaching T-c. The change of gamma(lambda) induces the corresponding rearrangement of the flux ...


Fragility Of Fermi Arcs In Dirac Semimetals, Yun Wu, Na Hyun Jo, Lin-Lin Wang, Connor A. Schmidt, Kathryn M. Neilson, Benjamin Schrunk, Przemyslaw Swatek, Andrew Eaton, Sergey L. Bud’Ko, Paul C. Canfield, Adam Kaminski Apr 2019

Fragility Of Fermi Arcs In Dirac Semimetals, Yun Wu, Na Hyun Jo, Lin-Lin Wang, Connor A. Schmidt, Kathryn M. Neilson, Benjamin Schrunk, Przemyslaw Swatek, Andrew Eaton, Sergey L. Bud’Ko, Paul C. Canfield, Adam Kaminski

Ames Laboratory Accepted Manuscripts

We use tunable, vacuum ultraviolet laser based angle-resolved photoemission spectroscopy and density functional theory (DFT) calculations to study the electronic properties of Dirac semimetal candidate cubic PtBi 2 . In addition to bulk electronic states we also find surface states in PtBi 2 , which is expected as PtBi 2 was theoretically predicated to be a candidate Dirac semimetal. The surface states are also well reproduced from DFT band calculations. Interestingly, the topological surface states form Fermi contours rather than double Fermi arcs that were observed in Na 3 Bi . The surface bands forming the Fermi contours merge with bulk bands in ...


Pressure-Temperature Phase Diagram Of The Eurbfe4as4 Superconductor, Li Xiang, Sergey L. Bud’Ko, Jin-Ke Bao, Duck Young Chung, Mercouri G. Kanatzidis, Paul C. Canfield Apr 2019

Pressure-Temperature Phase Diagram Of The Eurbfe4as4 Superconductor, Li Xiang, Sergey L. Bud’Ko, Jin-Ke Bao, Duck Young Chung, Mercouri G. Kanatzidis, Paul C. Canfield

Ames Laboratory Accepted Manuscripts

The pressure dependencies of the magnetic and superconducting transitions, as well as that of the superconducting upper critical field, are reported for single crystalline EuRbFe 4 As 4 . Resistance measurements were performed under hydrostatic pressures up to 6.21 GPa and in magnetic fields up to 9 T. Zero-field-cooled magnetization measurements were performed under hydrostatic pressures up to 1.24 GPa under 20 mT applied field. Superconducting transition temperature, T c , up to 6.21 GPa and magnetic transition temperature, T M , up to 1.24 GPa were obtained and a pressure-temperature phase diagram was constructed. Our results show that ...


Intelligent Metasurfaces With Continuously Tunable Local Surface Impedance For Multiple Reconfigurable Functions, Fu Liu, Odysseas Tsilipakos, Alexandros Pitilakis, Anna C. Tasolamprou, Mohammad Sajjad Mirmoosa, Nikolaos V. Kantartzis, Do-Hoon Kwon, Maria Kafesaki, Costas M. Soukoulis, Sergei A. Tretyakov Apr 2019

Intelligent Metasurfaces With Continuously Tunable Local Surface Impedance For Multiple Reconfigurable Functions, Fu Liu, Odysseas Tsilipakos, Alexandros Pitilakis, Anna C. Tasolamprou, Mohammad Sajjad Mirmoosa, Nikolaos V. Kantartzis, Do-Hoon Kwon, Maria Kafesaki, Costas M. Soukoulis, Sergei A. Tretyakov

Ames Laboratory Accepted Manuscripts

Electromagnetic metasurfaces can be characterized as intelligent if they are able to perform multiple tunable functions, with the desired response being controlled by a computer influencing the individual electromagnetic properties of each metasurface inclusion. In this paper, we present an example of an intelligent metasurface that operates in the reflection mode in the microwave frequency range. We numerically show that, without changing the main body of the metasurface, we can achieve tunable perfect absorption and tunable anomalous reflection. The tunability features can be implemented using mixed-signal integrated circuits (ICs), which can independently vary both the resistance and reactance, offering complete ...


Equation Of State Of Boron Nitride Combining Computation, Modeling, And Experiment, Shuai Zhang, Amy Lazicki, Burkhard Militzer, Lin H. Yang, Kyle Caspersen, Jim A. Gaffney, Markus W. Däne, John E. Pask, Walter R. Johnson, Abhiraj Sharma, Phanish Suryanarayana, Duane D. Johnson, Andrey V. Smirnov, Philip A. Sterne, David Erskine, Richard A. London, Federica Coppari, Damian Swift, Joseph Nilsen, Art J. Nelson, Heather D. Whitley Apr 2019

Equation Of State Of Boron Nitride Combining Computation, Modeling, And Experiment, Shuai Zhang, Amy Lazicki, Burkhard Militzer, Lin H. Yang, Kyle Caspersen, Jim A. Gaffney, Markus W. Däne, John E. Pask, Walter R. Johnson, Abhiraj Sharma, Phanish Suryanarayana, Duane D. Johnson, Andrey V. Smirnov, Philip A. Sterne, David Erskine, Richard A. London, Federica Coppari, Damian Swift, Joseph Nilsen, Art J. Nelson, Heather D. Whitley

Ames Laboratory Accepted Manuscripts

The equation of state (EOS) of materials at warm dense conditions poses significant challenges to both theory and experiment. We report a combined computational, modeling, and experimental investigation leveraging new theoretical and experimental capabilities to investigate warm-dense boron nitride (BN). The simulation methodologies include path integral Monte Carlo (PIMC), several density functional theory (DFT) molecular dynamics methods [plane-wave pseudopotential, Fermi operator expansion (FOE), and spectral quadrature (SQ)], activity expansion (actex), and all-electron Green's function Korringa-Kohn-Rostoker (mecca), and compute the pressure and internal energy of BN over a broad range of densities and temperatures. Our experiments were conducted at the ...


Measurements Of Μμ Pairs From Open Heavy Flavor And Drell-Yan In P + P Collisions At √S = 200 Gev, C. Aidala, Nicole J. Apadula, John C. Hill, Nels J. Hotvedt, 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, M. Shimomura, Arbin Timilsina, Et Al., Phenix Collaboration Apr 2019

Measurements Of Μμ Pairs From Open Heavy Flavor And Drell-Yan In P + P Collisions At √S = 200 Gev, C. Aidala, Nicole J. Apadula, John C. Hill, Nels J. Hotvedt, 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, M. Shimomura, Arbin Timilsina, Et Al., Phenix Collaboration

Physics and Astronomy Publications

PHENIX reports differential cross sections of mu mu pairs from semileptonic heavy-flavor decays and the Drell-Yan production mechanism measured in p + p collisions at root s = 200 GeV at forward and backward rapidity (1.2 < vertical bar eta vertical bar < 2.2). The mu mu pairs from c (c) over bar, b (b) over bar, and Drell-Yan are separated using a template fit to unlike- and like-sign muon pair spectra in mass and p(T). The azimuthal opening angle correlation between the muons from c (c ) over bar and b (b) over bar decays and the pair-p(T) distributions are compared to distributions generated using PYTHIA and POWHEG models, which both include next-to-leading order processes. The measured distributions for pairs from a are consistent with PYTHIA calculations. The c (c) over bar data present narrower azimuthal correlations and softer p(T) distributions compared to distributions generated from POWHEG. The b (b ) over bar data are well described by both models. The extrapolated total cross section for bottom production is 3.75 +/- 0.24(stat) +/-(0.35)(0.50) (syst) +/- 0.45(global) [mu b], which is consistent with previous measurements at the Relativistic Heavy Ion Collider in the same system at the same collision energy and is approximately a factor of 2 higher than the central value calculated with theoretical models. The measured Drell-Yan cross section is in good agreement with next-to-leading-order quantum-chromodynamics calculations.