Now showing items 1-20 of 24

    • 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 ...
    • Bound spinons in an antiferromagnetic S=1/2 chain with a staggered field 

      Kenzelmann, M.; Chen, Y.; Broholm, C.; Reich, D.H.; Qiu, Y. (American Physical Society, 2004-07-02)
      Inelastic neutron scattering was used to measure the magnetic field dependence of spin excitations in the antiferromagnetic S=1/2 chain CuCl2·2(dimethylsulfoxide) in the presence of uniform and staggered fields. Dispersive ...
    • Central mode and spin confinement near the boundary of the superconducting phase in YBa2Cu3O6.353 (Tc=18 K) 

      Birgeneau, R.J.; Broholm, C.; Liang, R.; Yamani, Z.; Bonn, D.; Tun, Z.; Chung, J.-H.; Hardy, W.N.; Stock, C.; Buyers, W.J.L. (American Physical Society, 2006-03-01)
      We have mapped the neutron scattering spin spectrum at low energies in YBa2Cu3O6.353 (Tc=18 K), where the doping ~0.06 is near the critical value (pc=0.055) for superconductivity. No coexistence with long-range-ordered ...
    • 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 ...
    • 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 ...
    • Evidence for decay of spin waves above the pseudogap of underdoped YBa2Cu3O6.35 

      Stock, C.; Cowley, R.A.; Buyers, W.J.L.; Coldea, R.; Broholm, C.; Frost, C.D.; Birgeneau, R.J.; Liang, R.; Bonn, D.; Hardy, W.N. (American Physical Society, 2007-05-01)
      The magnetic spectrum at high energies in heavily underdoped YBa2Cu3O6.35 (Tc=18 K) has been determined throughout the Brillouin zone. At low energy, the scattering forms a cone of spin excitations emanating from the ...
    • Field dependence of magnetic ordering in Kagome-staircase compound Ni3V2O8 

      Kenzelmann, M.; Harris, A.B.; Aharony, A.; Entin-Wohlman, O.; Yildirim, T.; Huang, Q.; Park, S.; Lawes, G.; Broholm, C.; Rogado, N.; Cava, R.J.; Kim, K.H.; Jorge, G.; Ramirez, A.P. (American Physical Society, 2006-07-01)
      We present powder and single-crystal neutron diffraction and bulk measurements of the Kagome-staircase compound Ni3V2O8 (NVO) in fields up to 8.5 T applied along the c direction. (The Kagome plane is the a-c plane.) This ...
    • 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 ...
    • Inhomogeneous level splitting in Pr2-xBixRu2O7 

      van Duijn, J.; Kim, K.H.; Hur, N.; Adroja, D.; Adams, M.A.; Huang, Q.Z.; Jaime, M.; Cheong, S.-W.; Broholm, C.; Perring, T.G. (American Physical Society, 2005-05-06)
      We report that Bi doping drives Pr2-xBixRu2O7 from an antiferromagnetic insulator (x=0) to a metallic paramagnet (x≈1) with a broad low T maximum in C/T. Neutron scattering reveals local low energy spin excitations (ℎω≈1 ...
    • 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 ...
    • Magnetic inversion symmetry breaking and ferroelectricity in TbMnO3 

      Kenzelmann, M.; Harris, A.B.; Jonas, S.; Broholm, C.; Schefer, J.; Kim, S.B.; Zhang, C.L.; Cheong, S.-W.; Vajk, O.P.; Lynn, J.W. (American Physical Society, 2005-08-19)
      TbMnO3 is an orthorhombic insulator where incommensurate spin order for temperature TN<41 K is accompanied by ferroelectric order for T<28 K. To understand this, we establish the magnetic structure above and below the ...
    • Magnetically driven ferroelectric order in Ni3V2O8 

      Lawes, G.; Harris, A.B.; Kimura, T.; Rogado, N.; Cava, R.J.; Aharony, A.; Entin-Wohlman, O.; Yildirim, T.; Kenzelmann, M.; Broholm, C.; Ramirez, A.P. (American Physical Society, 2005-08-19)
      We show that long-range ferroelectric and incommensurate magnetic order appear simultaneously in a single phase transition in Ni3V2O8. The temperature and magnetic-field dependence of the spontaneous polarization show a ...
    • 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) ...
    • Neutron scattering from a coordination polymer quantum paramagnet 

      Hong, T.; Kenzelmann, M.; Turnbull, M.M.; Landee, C.P.; Lewis, B.D.; Schmidt, K.P.; Uhrig, G.S.; Broholm, C.; Reich, D. (American Physical Society, 2006-09-01)
      Inelastic neutron scattering measurements are reported for a powder sample of the spin-1/2 quantum paramagnet Cu(quinoxaline)Br2. Magnetic neutron scattering is identified above an energy gap of 1.9 meV. Analysis of the ...
    • 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.; Chen, Y.1; Stone, M.B.1; Kenzelmann, M.1; 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 ...
    • Quantum criticality in an organic magnet 

      Stone, M.B.; Broholm, C.; Reich, D.H.; Tchernyshyov, O.; Vorderwisch, P.; Harrison, N. (American Physical Society, 2006-06-30)
      Exchange interactions between S=½ sites in piperazinium hexachlorodicuprate produce a frustrated bilayer magnet with a singlet ground state. We have determined the field-temperature phase diagram by high field magnetization ...
    • S=½ chain in a staggered field: high-energy bound-spinon state and the effects of a discrete lattice 

      Kenzelmann, M.; Batista, C.D.; Chen, Y.; Broholm, C.; Reich, D.H.; Park, S.; Qiu, Y. (American Physical Society, 2005-03-01)
      We report an experimental and theoretical study of the antiferromagnetic S=½ chain subject to uniform and staggered fields. Using inelastic neutron scattering, we observe a bound-spinon state at high energies in the linear ...
    • Spin gap and resonance at the nesting wave vector in superconducting FeSe0.4Te0.6 

      Qiu, Yiming; Bao, Wei; Zhao, Y.; Broholm, C.; 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 ...
    • 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 ...
    • 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 ...