Now showing items 1-20 of 20

    • 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 ...
    • Broken parity and a chiral ground state in the frustrated magnet CdCr2O4 

      Chern, G.-W.; Fennie, C.J.; Tchernyshyov, O. (American Physical Society, 2006-08-01)
      We present a model describing the lattice distortion and incommensurate magnetic order in the spinel CdCr2O4, a good realization of the Heisenberg 'pyrochlore' antiferromagnet. The magnetic frustration is relieved through ...
    • Dependence of exchange coupling on antiferromagnetic layer thickness in NiFe/CoO bilayers 

      Ambrose, T.; Chien, C.-L. (American Institute of Physics, 1998-06-01)
      A systematic study of the dependence of exchange coupling in NiFe/CoO bilayers on CoO layer thickness tAF from 5 to 500 Å has been made. For large CoO thicknesses (tAF>100 Å), the exchange field varies as 1/tAF, whereas ...
    • Doubly exchange-biased NiCoO/NiFe/Cu/NiFe/NiCoO spin valves 

      Ambrose, T.; Liu, K.; Chien, C.-L. (American Institute of Physics, 1999-04-15)
      A new type of doubly exchange-biased Ni50Co50O/NiFe/Cu/NiFe/Ni30Co70O spin-valve structure, with two ferromagnetic layers exchange biased in opposite directions by two different antiferromagnetic layers is demonstrated. ...
    • Fermionic spin excitations in two- and three-dimensional antiferromagnets 

      Zhihao, Hao; Tchernyshyov, O. (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 ...
    • 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 ...
    • Long-range exchange coupling between a ferromagnet and an antiferromagnet across a nonmagnetic spacer layer 

      Gokemeijer, N.J.; Ambrose, T.; Chien, C.-L.; Wang, N.; Fung, K.K. (American Institute of Physics, 1997-04-15)
      The antiferromagnet/ferromagnet exchange coupling giving rise to a shifted hysteresis loop has usually been considered an interfacial effect. We show evidence that this exchange coupling between an antiferromagnet (CoO) ...
    • Longitudinal and perpendicular exchange bias in FeMn/(FeNi/FeMn)n multilayers 

      Sun, L.; Zhou, S.M.; Searson, P.C.; Chien, C.-L. (American Institute of Physics, 2003-05-15)
      Exchange bias in ferromagnetic (FM)/antiferromagnetic (AF) bilayers is usually investigated in the longitudinal configuration with the exchange coupling established in the film plane. In this work, we report on the ...
    • 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 ...
    • 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) ...
    • Partial order from disorder in a classical pyrochlore antiferromagnet 

      Chern, G.-W.; 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 ...
    • 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-trimer antiferromagnetism in La4Cu3MoO12 

      Qiu, Y.; Broholm, C.; Ishiwata, S.; Azuma, M.; Takano, M.; Bewley, R.; Buyers, W.J.L. (American Physical Society, 2005-06-01)
      La4Cu3MoO12 is a cluster antiferromagnet where copper spin-1/2 trimers form a network of strongly coupled spin trimers. The magnetic properties of this material have been examined using magnetic neutron scattering. At low ...
    • Spinons in the strongly correlated copper oxide chains in SrCuO2 

      Broholm, C.; Perring, T.G.; Takagi, H.; Frost, C.D.; Zaliznyak, L.A.; Woo, H. (American Physical Society, 2004-08-20)
      We have investigated the spin dynamics in the strongly correlated chain copper oxide SrCuO2 for energies up to ≥0.6 eV using inelastic neutron scattering. We observe a gapless continuum of magnetic excitations, which is ...
    • Strong magnetic fluctuations in transition metal oxides 

      Aeppli, G.; Lee, S.-H.; Broholm, C.; DiTusa, J.F.; Bao, W. (American Institute of Physics, 1996-04-15)
      Most magnets have long-range magnetic order when the thermal energy is less than the local magnetic exchange energy (T<|ΘCW|) effects such as reduced dimensionality and frustration, 1 however, can suppress the ordering ...