Now showing items 41-58 of 58

    • Phase diagram and spin Hamiltonian of weakly-coupled anisotropic S=½ chains in CuCl2·2((CD3)2SO) 

      Chen, Y.; Stone, M. B.; Kenzelmann, M.; Batista, C. D.; Reich, D.H.; Broholm, C. (American Physical Society, 2007-06-01)
      Field-dependent specific heat and neutron scattering measurements were used to explore the antiferromagnetic S=½ chain compound CuCl2·2((CD3)2SO). At zero field the system acquires magnetic long-range order below TN=0.93 ...
    • Direct transition from a disordered to a multiferroic phase on a triangular lattice 

      Kenzelmann, M.; Lawes, G.; Harris, A. B.; Gasparovic, G.; Broholm, C.; Ramirez, A. P.; Jorge, G.A.; Jaime, M.; Park, S.; Huang, Q.; Shapiro, A. Y.; Demianets, L. A. (American Physical Society, 2007-06-29)
      We report the first direct transition from a paramagnetic and paraelectric phase to an incommensurate multiferroic in the triangular lattice antiferromagnet RbFe(MoO4)2. Ferroelectricity is observed only when the magnetic ...
    • Ising phases of Heisenberg ladders in a magnetic field 

      Penc, Karlo; Fouet, Jean-Baptiste; Miyahara, Shin; Tchernyshyov, Oleg; Mila, Frédéric (American Physical Society, 2007-09-14)
      We show that Dzyaloshinskii-Moriya (DM) interactions can substantially modify the phase diagram of spin-1/2 Heisenberg ladders in a magnetic field provided they compete with exchange. For nonfrustrated ladders, they induce ...
    • From cooperative paramagnetism to Neel order in Y2Ru2O7: neutron scattering measurements 

      van Duijn, J.; Hur, N.; Taylor, J. W.; Qiu, Y.; Huang, Q.Z.; Cheong, S.-W.; Broholm, C.; Perring, T.G. (American Physical Society, 2008-01-01)
      Spin correlations in the pyrochlore antiferromagnet Y2Ru2O7 with Curie-Weiss temperature ΘCW* - 1100 K and critical temperature TN = 77 K were examined through neutron scattering. For TN < T < ΘCW / 3 the data show spin ...
    • Spin resonance in the d-wave superconductor CeCoIn5 

      Stock, C.; Broholm, C.; Hudis, J.; Kang, H. J.; Petrovic, C. (American Physical Society, 2008-02-29)
      Neutron scattering is used to probe antiferromagnetic spin fluctuations in the d-wave heavy fermion superconductor CeCoIn5 (Tc=2.3 K). Superconductivity develops from a state with slow (ℎΓ=0.3±0.15 meV) commensurate ...
    • Exploiting finite size effects in a novel core/shell microstructure 

      Liu, Zhu; Xia, Guoqiang; Zhu, Frank; Kim, Su; Markovic, Nina; Chien, Chia-Ling; Searson, Peter C. (American Institute of Physics, 2008-03-15)
      Electrodeposition of Ni-Cu alloys at high Cu(II) concentration and large overpotentials results in phase separation with a unique microstructure characterized by features with a copper-rich core and a nickel-rich shell. ...
    • Dynamics of domain walls in magnetic nanostrips 

      Tretiakov, O. A.; Clarke, D.; Chern, Gai-Wei; Bazaliy, Ya.B.; Tchernyshyov, O. (American Physical Society, 2008-03-28)
      We express the dynamics of domain walls in ferromagnetic nanowires in terms of collective coordinates, generalizing Thiele[psila]s steady-state results. For weak external perturbations the dynamics is dominated by a few ...
    • Partial order from disorder in a classical pyrochlore antiferromagnet 

      Chern, Gia-Wei; Moessner, R.; Tchernyshyov, O. (American Physical Society, 2008-10-01)
      We investigate theoretically the phase diagram of a classical Heisenberg antiferromagnet on the pyrochlore lattice perturbed by a weak second-neighbor interaction J2. The huge ground-state degeneracy of the nearest-neighbor ...
    • Dynamics of a vortex domain wall in a magnetic nanostrip: application of the collective-coordinate approach 

      Clarke, D.J.; Tretiakov, O. A.; Chern, G.-W.; Bazaliy, Ya.B.; Tchernyshyov, O. (American Physical Society, 2008-10-01)
      The motion of a vortex domain wall in a ferromagnetic strip of submicron width under the influence of an external magnetic field exhibits three distinct dynamical regimes. In a viscous regime at low fields the wall moves ...
    • Anisotropic three-dimensional magnetism in CaFe2As2 

      McQueeney, R. J.; Diallo, S. O.; Antropov, V. P.; Samolyuk, G. D.; Broholm, C.; Ni, N.; Nandi, S.; Yethiraj, M.; Zaretsky, J.L.; Pulikkotil, J. J.; Kreyssig, A.; Lumsden, M.D.; Harmon, B. N.; Canfield, P.C. (American Physical Society, 2008-11-28)
      Inelastic neutron scattering measurements of the magnetic excitations in CaFe2As2 indicate that the spin wave velocity in the Fe layers is exceptionally large and similar in magnitude to the cuprates. However, the spin ...
    • Current and shot noise measurements in a carbon nanotube-based spin diode 

      Merchant, Christopher A.; Markovic, Nina (American Institute of Physics, 2009-04-01)
      Low-temperature measurements of asymmetric carbon nanotube (CNT) quantum dots are reported. The CNTs are end-contacted with one ferromagnetic and one normal-metal electrode. The measurements show a spin-dependent rectification ...
    • Effects of carrier mobility and morphology in organic semiconductor spin valves 

      Liu, Yaohua; Lee, Taegweo; Katz, Howard E.; Reich, Daniel H. (American Institute of Physics, 2009-05-01)
      We studied spin transport in four organic semiconductors (OSCs) with different electronic properties. Magnetoresistance (MR) effects were observed up to room temperature in junctions based on an electron-carrying OSC, ...
    • Itinerant magnetic excitations in antiferromagnetic CaFe2As2 

      Diallo, S. O.; Antropov, V. P.; Perring, T.G.; Broholm, C.; Pulikkotil, J. J.; Ni, N.; Bud'ko, S.L.; Canfield, P.C.; Kreyssig, A.; Goldman, A. I.; McQueeney, R. J. (American Physical Society, 2009-05-08)
      Neutron scattering measurements of the magnetic excitations in single crystals of antiferromagnetic CaFe2As2 reveal steeply dispersive and well-defined spin waves up to an energy of ~100 meV. Magnetic excitations above 100 ...
    • Spin-lattice order in frustrated ZnCr2O4 

      Ji, S.; Lee, S.-H.; Broholm, C.; Koo, T. Y.; Ratcliff, W.; Cheong, S.-W.; Zschack, P. (American Physical Society, 2009-07-17)
      Using synchrotron x-ray and neutron diffraction, we disentangle spin-lattice order in highly frustrated ZnCr2O4 where magnetic chromium ions occupy the vertices of regular tetrahedra. Upon cooling below 12.5 K the quandary ...
    • Spin gap and resonance at the nesting wave vector in superconducting FeSe0.4Te0.6 

      Qiu, Yiming; Bao, Wei; Zhao, Y.; Broholm, Collin; Stanev, V.; Tesanovic, Z.; Gasparovic, Y. C.; Chang, S.; Hu, Jin; Qian, Bin; Fang, Minghu; Mao, Zhiqiang (American Physical Society, 2009-08-07)
      Neutron scattering is used to probe magnetic excitations in FeSe0.4Te0.6 (Tc = 14 K). Low energy spin fluctuations are found with a characteristic wave vector (1212L) that corresponds to Fermi surface nesting and differs ...
    • Coupled Magnetic and Ferroelectric Domains in Multiferroic Ni3V2O8 

      Chen, W. C.; Kenzelmann, M.; Gentile, T. R.; Chen, Y.; Cabrera, I.; Rogado, N.; Lawes, G.; Broholm, C.; Lynn, J. W.; Erwin, R.; Cava, R.J.; Leao, J. B. (American Physical Society, 2009-08-21)
      Electric control of multi-ferroic domains is demonstrated through polarized magnetic neutron diffraction. Cooling to the cycloidal multi-ferroic phase of Ni3V2O8 in an electric field E causes the incommensurate Bragg ...
    • Neutron scattering evidence for isolated spin-1/2 ladders in (C5D12N)2CuBr4 

      Nagler, S. E.; Pajerowski, D. M.; Meisel, M. W.; Broholm, C.; Schmidt, K. P.; Talham, D. R.; Brown, C.M.; Uhrig, G. S.; Savici, A.T.; Granroth, G. E. (American Physical Society, 2009-09-01)
      Inelastic neutron scattering was used to determine the spin Hamiltonian for the singlet ground-state system of fully deuterated BPCB, (C5D12N)2CuBr4. A two-leg spin-1/2 ladder model, with J⊥=(1.09±0.01) meV and J∥=(0.296±0.005) ...
    • Fermionic spin excitations in two- and three-dimensional antiferromagnets 

      Zhihao, Hao; Tchernyshyov, Oleg (American Physical Society, 2009-10-30)
      Spin excitations in an ordered Heisenberg magnet are magnons-bosons with spin 1. That may change when frustration and quantum fluctuations suppress the order and restore the spin-rotation symmetry. We show that spin ...