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Articles 1 - 27 of 27
Full-Text Articles in Physical Sciences and Mathematics
Domain-Wall Tunneling Electroresistance Effect, M. Li, L. L. Tao, Evgeny Y. Tsymbal
Domain-Wall Tunneling Electroresistance Effect, M. Li, L. L. Tao, Evgeny Y. Tsymbal
Department of Physics and Astronomy: Faculty Publications
Ferroelectric tunnel junctions (FTJs) utilizing an in-plane head-to-head ferroelectric domain wall (DW) have recently been realized, showing interesting physics and new functionalities. However, the DW state in these junctions was found to be metastable and not reversible after applying an electric field. In this work, we demonstrate that a stable and reversible head-to-head DW state can be achieved in FTJs by proper engineering of polar interfaces. Using density functional theory (DFT) calculations and phenomenological modeling, we explore the DW stability by varying stoichiometry of the La1−xSrxO=TiO2 interfaces in FTJs with La0.5Sr0.5 …
Search For Physics Beyond The Standard Model In Events With Overlapping Photons And Jets, A. M. Sirunyan
Search For Physics Beyond The Standard Model In Events With Overlapping Photons And Jets, A. M. Sirunyan
Department of Physics and Astronomy: Faculty Publications
Results are reported from a search for new particles that decay into a photon and two gluons, in events with jets. Novel jet substructure techniques are developed that allow photons to be identified in an environment densely populated with hadrons. The analyzed proton-proton collision data were collected by the CMS experiment at the LHC, in 2016 at √s = 13 TeV, and correspond to an integrated luminosity of 35.9 fb−1. The spectra of total transverse hadronic energy of candidate events are examined for deviations from the standard model predictions. No statistically significant excess is observed over the expected …
Search For Low-Mass Quark-Antiquark Resonances Produced In Association With A Photon At √S =13 Tev, A. M. Sirunyan
Search For Low-Mass Quark-Antiquark Resonances Produced In Association With A Photon At √S =13 Tev, A. M. Sirunyan
Department of Physics and Astronomy: Faculty Publications
A search for narrow low-mass resonances decaying to quark-antiquark pairs is presented. The search is based on proton-proton collision events collected at 13 TeV by the CMS detector at the CERN LHC. The data sample corresponds to an integrated luminosity of 35.9 fb−1, recorded in 2016. The search considers the case where the resonance has high transverse momentum due to initial-state radiation of a hard photon. To study this process, the decay products of the resonance are reconstructed as a single large-radius jet with two-pronged substructure. The signal would be identified as a localized excess in the jet …
Two-Dimensional Spin-Valley Locking Spin Valve, L. L. Tao, Evgeny Y. Tsymbal
Two-Dimensional Spin-Valley Locking Spin Valve, L. L. Tao, Evgeny Y. Tsymbal
Department of Physics and Astronomy: Faculty Publications
Valleytronics is an emerging field of research which employs energy valleys in the band structure of two-dimensional (2D) electronic materials to encode information. A special interest has been triggered by the associated spin-valley coupling which reveals rich fundamental physics and enables new functionalities. Here, we propose exploiting the spin-valley locking in 2D materials with a large spin-orbit coupling and electric-field reversible valley spin polarization, such as germanene, stanene, a 1T' transition metal dichalcogenide (TMDC) monolayer, and a 2H-TMDC bilayer, to realize a valley spin valve (VSV). The valley spin polarization in these materials can be switched by …
Search For A Light Charged Higgs Boson Decaying To A W Boson And A Cp-Odd Higgs Boson In Final States With Eμμ Or Μμμ In Proton-Proton Collisions At √S =13 Tev, A. M. Sirunyan
Department of Physics and Astronomy: Faculty Publications
A search for a light charged Higgs boson (H+) decaying to a W boson and a CP-odd Higgs boson (A) in final states with eμμ or μμμ is performed using data from pp collisions at √s = 13 TeV, recorded by the CMS detector at the LHC and corresponding to an integrated luminosity of 35.9 fb−1. In this search, it is assumed that the H+ boson is produced in decays of top quarks, and the A boson decays to two oppositely charged muons. The presence of signals for H+ boson masses …
Diffractive Imaging Of Dissociation And Ground-State Dynamics In A Complex Molecule, Kyle J. Wilkin, Robert M. Parrish, Jie Yang, Thomas J. A. Wolf, J. Pedro F. Nunes, Markus Guehr, Renkai Li, Xiaozhe Shen, Qiang Zheng, Xijie Wang, Todd J. Martinez, Martin Centurion
Diffractive Imaging Of Dissociation And Ground-State Dynamics In A Complex Molecule, Kyle J. Wilkin, Robert M. Parrish, Jie Yang, Thomas J. A. Wolf, J. Pedro F. Nunes, Markus Guehr, Renkai Li, Xiaozhe Shen, Qiang Zheng, Xijie Wang, Todd J. Martinez, Martin Centurion
Department of Physics and Astronomy: Faculty Publications
We have investigated the structural dynamics in photoexcited 1,2-diiodotetrafluoroethane molecules (C2F4I2 ) in the gas phase experimentally using ultrafast electron diffraction and theoretically using FOMO-CASCI excited-state dynamics simulations. The molecules are excited by an ultraviolet femtosecond laser pulse to a state characterized by a transition from the iodine 5p⊥ orbital to a mixed 5p ‖ σ hole and CF•2 antibonding orbital, which results in the cleavage of one of the carbon-iodine bonds. We have observed, with sub-Angstrom resolution, the motion of the nuclear wave packet of the dissociating iodine atom followed …
Magneto - Electric Logic Devices Using Semiconductor Channel With Large Spin - Orbit Coupling, Dmitri E. Nikonov, Christian H. Binek, Xia Hong, Jonathan P. Bird, Kang L. Wang, Peter L. Dowben
Magneto - Electric Logic Devices Using Semiconductor Channel With Large Spin - Orbit Coupling, Dmitri E. Nikonov, Christian H. Binek, Xia Hong, Jonathan P. Bird, Kang L. Wang, Peter L. Dowben
Department of Physics and Astronomy: Faculty Publications
Antiferromagnetic magneto - electric spin - orbit read ( AF SOR ) logic devices are presented . The devices include a voltage - controlled magnetoelectric ( ME ) layer that switches polarization in response to an electric field from the applied voltage and a narrow channel conductor of a spin - orbit coupling ( SOC ) material on the ME layer . One or more sources and one or more drains , each optionally formed of ferromagnetic material , are provided on the SOC material .
Resonance Electron Interaction With Five-Membered Heterocyclic Compounds: Vibrational Feshbach Resonances And Hydrogen-Atom Stripping, Stanislav A. Pshenichnyuk, Ilya I. Fabrikant, Alberto Modelli, Sylwia Ptasińska, Alexei S. Komolov
Resonance Electron Interaction With Five-Membered Heterocyclic Compounds: Vibrational Feshbach Resonances And Hydrogen-Atom Stripping, Stanislav A. Pshenichnyuk, Ilya I. Fabrikant, Alberto Modelli, Sylwia Ptasińska, Alexei S. Komolov
Department of Physics and Astronomy: Faculty Publications
Low-energy (0–15 eV) resonance electron attachment to a series of five-membered heterocyclic rings (isoxazole, imidazole, pyrazole, pyrrole, 1-methyl-, and 2-methylimidazole) is studied under gas-phase conditions by means of electron transmission spectroscopy and dissociative electron attachment spectroscopy (DEAS). Experimental spectral features are assigned on the basis of Hartree-Fock and density functional theory calculations. Sharp features, with a width of less than 0.1 eV, observed in the electron transmission spectra of imidazole, pyrazole, and pyrrole close to 0.45 eV, i.e., well below the energy of their lowest-lying π∗ shape resonances detected at 1.90, 1.87, and 2.33 eV, respectively, are associated with …
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
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
Department of Physics and Astronomy: Faculty Publications
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 …
Studies Of Beauty Suppression Via Nonprompt D0 Mesons In Pb-Pb Collisions At √SNn =5.02 Tev, A. M. Sirunyan
Studies Of Beauty Suppression Via Nonprompt D0 Mesons In Pb-Pb Collisions At √SNn =5.02 Tev, A. M. Sirunyan
Department of Physics and Astronomy: Faculty Publications
The transverse momentum spectra of D0 mesons from b hadron decays are measured at midrapidity (|y| < 1) in pp and Pb-Pb collisions at a nucleon-nucleon center of mass energy of 5.02 TeV with the CMS detector at the LHC. The D0 mesons from b hadron decays are distinguished from prompt D0 mesons by their decay topologies. In Pb-Pb collisions, the B → D0 yield is found to be suppressed in the measured pT range from 2 to 100 GeV=c as compared to pp collisions. The suppression is weaker than that of prompt D0 mesons and charged hadrons …
Classical Theory Of Laser-Assisted Spontaneous Bremsstrahlung, H. B. Ambalampitiya, Ilya I. Fabrikant
Classical Theory Of Laser-Assisted Spontaneous Bremsstrahlung, H. B. Ambalampitiya, Ilya I. Fabrikant
Department of Physics and Astronomy: Faculty Publications
We study the process of laser-assisted spontaneous electron bremsstrahlung by running classical trajectories in a combined Coulomb and laser (ac) fields. Due to chaotic scattering in the combined Coulomb and ac fields, the radiation probability as a function of the impact parameter and the constant phase of the laser field exhibits fractal structures. However, these structures are smeared out when the cross section is integrated over the impact parameter and averaged over the phase. We analyze the role of different types of orbits, including the trapped orbits, and the dependence of the radiation probability on the impact parameter and the …
Ambient Conditions Disordered-Ordered Phase Transition Of Two-Dimensional Interfacial Water Molecules Dependent On Charge Dipole Moment, Chunlei Wang, Chonghai Qi, Yusong Tu, Xuechuan Nie, Shanshan Liang
Ambient Conditions Disordered-Ordered Phase Transition Of Two-Dimensional Interfacial Water Molecules Dependent On Charge Dipole Moment, Chunlei Wang, Chonghai Qi, Yusong Tu, Xuechuan Nie, Shanshan Liang
Department of Physics and Astronomy: Faculty Publications
Phase transitions of water molecules are commonly expected to occur only under extreme conditions, such as nanoconfinement, high pressure, or low temperature. We herein report the disordered-ordered phase transition of two-dimensional interfacial water molecules under ambient conditions using molecular-dynamics simulations. This phase transition is greatly dependent on the charge dipole moment, production of both charge values, and the dipole length of the solid surface. The phase transition can be identified by a sharp change in water-water interaction energies and the order parameters of the two-dimensional interfacial water monolayer, under a tiny dipole moment change near the critical dipole moment. The …
Search For W Boson Decays To Three Charged Pions, A. M. Sirunyan
Search For W Boson Decays To Three Charged Pions, A. M. Sirunyan
Department of Physics and Astronomy: Faculty Publications
For the first time, a search for the rare decay of the W boson to three charged pions has been performed. Proton-proton collision data recorded by the CMS experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 77.3 fb−1, have been analyzed. No significant excess is observed above the background expectation. An upper limit of 1.01 × 10−6 is set at 95% confidence level on the branching fraction of the W boson to three charged pions. This provides a strong motivation for theoretical calculations of this branching fraction.
Jet Shapes Of Isolated Photon-Tagged Jets In Pb-Pb And Pp Collisions At √SNn=5.02 Tev, A. M. Sirunyan
Jet Shapes Of Isolated Photon-Tagged Jets In Pb-Pb And Pp Collisions At √SNn=5.02 Tev, A. M. Sirunyan
Department of Physics and Astronomy: Faculty Publications
The modification of jet shapes in Pb-Pb collisions, relative to those in pp collisions, is studied for jets associated with an isolated photon. The data were collected with the CMS detector at the LHC at a nucleon-nucleon center-of-mass energy of 5.02 TeV. Jet shapes are constructed from charged particles with track transverse momenta (pT ) above 1 GeV/c in annuli around the axes of jets with pjetT > 30 GeV/c associated with an isolated photon with pγT > 60 GeV/c. The jet shape distributions are consistent between peripheral Pb-Pb and pp collisions, …
Testing Quantum Coherence In Stochastic Electrodynamics With Squeezed Schrödinger Cat States, Wayne Cheng-Wei Huang, Herman Batelaan
Testing Quantum Coherence In Stochastic Electrodynamics With Squeezed Schrödinger Cat States, Wayne Cheng-Wei Huang, Herman Batelaan
Department of Physics and Astronomy: Faculty Publications
The interference pattern in electron double-slit diffraction is a hallmark of quantum mechanics. A long-standing question for stochastic electrodynamics (SED) is whether or not it is capable of reproducing such effects, as interference is a manifestation of quantum coherence. In this study, we used excited harmonic oscillators to directly test this quantum feature in SED. We used two counter-propagating dichromatic laser pulses to promote a ground-state harmonic oscillator to a squeezed Schrödinger cat state. Upon recombination of the two well-separated wavepackets, an interference pattern emerges in the quantum probability distribution but is absent in the SED probability distribution. We thus …
Observation Of Single Top Quark Production In Association With A Z Boson In Proton-Proton Collisions At √S = 13 Tev, A. M. Sirunyan
Observation Of Single Top Quark Production In Association With A Z Boson In Proton-Proton Collisions At √S = 13 Tev, A. M. Sirunyan
Department of Physics and Astronomy: Faculty Publications
The observation of single top quark production in association with a Z boson and a quark (tZq) is reported. Events from proton-proton collisions at a center-of-mass energy of 13 TeV containing three charged leptons (either electrons or muons) and at least two jets are analyzed. The data were collected with the CMS detector in 2016 and 2017 and correspond to an integrated luminosity of 77.4fb−1. The increased integrated luminosity, a multivariate lepton identification, and a redesigned analysis strategy improve significantly the sensitivity of the analysis compared to previous searches for tZq production. The tZq signal is …
Observation Of Two Excited B+C States And Measurement Of The B+C (2s) Mass In Pp Collisions At √S = 13 Tev, A. M. Sirunyan
Observation Of Two Excited B+C States And Measurement Of The B+C (2s) Mass In Pp Collisions At √S = 13 Tev, A. M. Sirunyan
Department of Physics and Astronomy: Faculty Publications
Signals consistent with the B+c (2S) and B*c+(2S) states are observed in proton-proton collisions at √s = 13 TeV, in an event sample corresponding to an integrated luminosity of 143 fb−1, collected by the CMS experiment during the 2015–2018 LHC running periods. These excited []c states are observed in the B+c π+π− invariant mass spectrum, with the ground state B+c reconstructed through its decay to J/ψπ+. The two states are reconstructed as two well-resolved peaks, separated in mass by 29.1 ± 1.5(stat) ± …
Combination Of Searches For Higgs Boson Pair Production In Proton-Proton Collisions At √S = 13 Tev, A. M. Sirunyan
Combination Of Searches For Higgs Boson Pair Production In Proton-Proton Collisions At √S = 13 Tev, A. M. Sirunyan
Department of Physics and Astronomy: Faculty Publications
This Letter describes a search for Higgs boson pair production using the combined results from four final states: bbγγ, bbττ, bbbb, and bbVV, where V represents a W or Z boson. The search is performed using data collected in 2016 by the CMS experiment from LHC proton-proton collisions at √s = 13 TeV, corresponding to an integrated luminosity of 35.9 fb−1. Limits are set on the Higgs boson pair production cross section. A 95% confidence level observed (expected) upper limit on the nonresonant production cross section is set at 22.2 (12.8) times the standard model …
Valley-Dependent Lorentz Force And Aharonov-Bohm Phase In Strained Graphene P-N Junction, Sanjay Prabhakar, Rabindra Nepal, Roderick Melnik, Alexey Kovalev
Valley-Dependent Lorentz Force And Aharonov-Bohm Phase In Strained Graphene P-N Junction, Sanjay Prabhakar, Rabindra Nepal, Roderick Melnik, Alexey Kovalev
Department of Physics and Astronomy: Faculty Publications
Veselago lens focusing in graphene p−n junction is promising for realizations of new generation electron optics devices. However, the effect of the strain-induced Aharonov-Bohm interference in a p−n junction has not been discussed before. We provide an experimentally feasible setup based on the Veselago lens in which the presence of strain can result in both the valley-dependent Lorentz force and Aharonov-Bohm interference. In particular, by employing the Green's function and tight-binding methods, we study the strain induced by dislocations and line defects in a p−n junction and show how the resulting Aharonov-Bohm phase and interference can be detected. Furthermore, for …
Influence Of Strain And Chemical Substitution On The Magnetic Anisotropy Of Antiferromagnetic Cr2O3: An Ab-Initio Study, Sai Mu, Kirill D. Belashchenko
Influence Of Strain And Chemical Substitution On The Magnetic Anisotropy Of Antiferromagnetic Cr2O3: An Ab-Initio Study, Sai Mu, Kirill D. Belashchenko
Department of Physics and Astronomy: Faculty Publications
The influence of the mechanical strain and chemical substitution on the magnetic anisotropy energy (MAE) of Cr2O3 is studied using first-principles calculations. Dzyaloshinskii-Moriya interaction contributes substantially to MAE by inducing spin canting when the antiferromagnetic order parameter is not aligned with the hexagonal axis. Nearly cubic crystal field results in a very small MAE in pure Cr2O3 at zero strain, which is incorrectly predicted to be negative (in-plane) on account of spin canting. The MAE is strongly modified by epitaxial strain, which tunes the crystal-field splitting of the t2g triplet. The contribution from …
Search For Narrow Hγ Resonances In Proton-Proton Collisions At √S =13 Tev, A. M. Sirunyan
Search For Narrow Hγ Resonances In Proton-Proton Collisions At √S =13 Tev, A. M. Sirunyan
Department of Physics and Astronomy: Faculty Publications
A search for heavy, narrow resonances decaying to a Higgs boson and a photon (Hγ) has been performed in proton-proton collision data at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb−1 collected with the CMS detector at the LHC in 2016. Events containing a photon and a Lorentz-boosted hadronically decaying Higgs boson reconstructed as a single, large-radius jet are considered, and the γ + jet invariant mass spectrum is analyzed for the presence of narrow resonances. To increase the sensitivity of the search, events are categorized depending on whether or not …
Exceptional Points And Spectral Singularities In Active Epsilon-Near-Zero Plasmonic Waveguides, Ying Li, Christos Argyropoulos
Exceptional Points And Spectral Singularities In Active Epsilon-Near-Zero Plasmonic Waveguides, Ying Li, Christos Argyropoulos
Department of Physics and Astronomy: Faculty Publications
The intriguing physics of exceptional points (EPs) and spectral singularities in open (non-Hermitian) active photonic systems has recently sparked increased interest among the research community. These spectral degeneracies have been obtained in asymmetric active and passive photonic configurations but their demonstration with symmetric active plasmonic structures still remains elusive. In this paper, we present a nanoscale active plasmonic waveguide system consisting of an array of periodic slits that can exhibit exceptional points and spectral singularities leading to several functionalities. The proposed symmetric active system operates near its cutoff wavelength and behaves as an effective epsilon-near-zero (ENZ) medium. We demonstrate the …
Systems And Methods For Scalable Perovskite Device Fabrication, Jinsong Huang, Qingfeng Dong, Yuchuan Shao
Systems And Methods For Scalable Perovskite Device Fabrication, Jinsong Huang, Qingfeng Dong, Yuchuan Shao
Department of Physics and Astronomy: Faculty Publications
Continuous processes for fabricating a perovskite device are described that include forming a perovskite layer or film on a substrate using a linear deposition device , and optionally using a conductive tape lamination process to form an anode or a cathode layer on the perovskite device .
Search For The Higgs Boson Decaying To Two Muons In Proton-Proton Collisions At √S =13 Tev, A. M. Sirunyan
Search For The Higgs Boson Decaying To Two Muons In Proton-Proton Collisions At √S =13 Tev, A. M. Sirunyan
Department of Physics and Astronomy: Faculty Publications
A search for the Higgs boson decaying to two oppositely charged muons is presented using data recorded by the CMS experiment at the CERN LHC in 2016 at a center-of-mass energy √s = 13 TeV, corresponding to an integrated luminosity of 35.9 fb−1. Data are found to be compatible with the predicted background. For a Higgs boson with a mass of 125.09 GeV, the 95% confidence level observed (background-only expected) upper limit on the production cross section times the branching fraction to a pair of muons is found to be 3.0 (2.5) times the standard model expectation. In …
Search For Dark Matter Particles Produced In Association With A Top Quark Pair At √S =13 Tev, A. M. Sirunyan
Search For Dark Matter Particles Produced In Association With A Top Quark Pair At √S =13 Tev, A. M. Sirunyan
Department of Physics and Astronomy: Faculty Publications
A search is performed for dark matter particles produced in association with a top quark pair in proton-proton collisions at √s = 13 TeV. The data correspond to an integrated luminosity of 35.9 fb−1 recorded by the CMS detector at the LHC. No significant excess over the standard model expectation is observed. The results are interpreted using simplified models of dark matter production via spin-0 mediators that couple to dark matter particles and to standard model quarks, providing constraints on the coupling strength between the mediator and the quarks. These are the most stringent collider limits to date for …
Magnetoelectric Control Of Topological Phases In Graphene, Hiroyuki Takenaka, Shane Sandhoefner, Alexey Kovalev, Evgeny Tsymbal
Magnetoelectric Control Of Topological Phases In Graphene, Hiroyuki Takenaka, Shane Sandhoefner, Alexey Kovalev, Evgeny Tsymbal
Department of Physics and Astronomy: Faculty Publications
Topological antiferromagnetic (AFM) spintronics is an emerging field of research, which involves the topological electronic states coupled to the AFM order parameter known as the Néel vector. The control of these states is envisioned through manipulation of the Néel vector by spin-orbit torques driven by electric currents. Here we propose a different approach favorable for low-power AFM spintronics, where the control of the topological states in a two-dimensional material, such as graphene, is performed via the proximity effect by the voltage induced switching of the Néel vector in an adjacent magnetoelectric AFM insulator, such as chromia. Mediated by the symmetry …
Duality And Free Energy Analyticity Bounds For Few-Body Ising Models With Extensive Homology Rank, Yi Jiang, Ilya Dumer, Alexey Kovalev, Leonid Pryadko
Duality And Free Energy Analyticity Bounds For Few-Body Ising Models With Extensive Homology Rank, Yi Jiang, Ilya Dumer, Alexey Kovalev, Leonid Pryadko
Department of Physics and Astronomy: Faculty Publications
We consider pairs of few-body Ising models where each spin enters a bounded number of interaction terms (bonds) such that each model can be obtained from the dual of the other after freezing k spins on large-degree sites. Such a pair of Ising models can be interpreted as a two-chain complex with k being the rank of the first homology group. Our focus is on the case where k is extensive, that is, scales linearly with the number of bonds n. Flipping any of these additional spins introduces a homologically nontrivial defect (generalized domain wall). In the presence of …