Now showing items 21-40 of 58

    • 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 ...
    • 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 ...
    • 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 ...
    • 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 ...
    • Spin-trimer antiferromagnetism in La4Cu3MoO12 

      Qiu, Y.; Broholm, C.; Ishiwata, S.; Azuma, M.; Takano, M.; Bewley, R.; Buyers, W.J.L.; 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 ...
    • 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 ...
    • 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 ...
    • Composite domain walls in flat nanomagnets: the magnetostatic limit 

      Youk, H.; Chern, G.-W.; Merit, K.; Oppenheimer, B.; Tchernyshyov, O. (American Institute of Physics, 2006-04-15)
      We discuss the structure of the so-called 'vortex' domain walls in soft magnetic nanoparticles. A wall of this kind is a composite object consisting of three elementary topological defects: two edge defects with winding ...
    • Topological defects in flat nanomagnets: the magnetostatic limit 

      Chern, G.-W.; Youk, H.; Tchernyshyov, O. (American Institute of Physics, 2006-04-15)
      We discuss elementary topological defects in soft magnetic nanoparticles in the thin-film geometry. In the limit dominated by magnetostatic forces the low-energy defects are vortices (winding number n=+1), cross ties (n=-1), ...
    • Magnetic properties of one-dimensional quasiperiodic Co/Pt multilayers 

      Zhu, L.Y.; Cheng, X.M.; Chien, C.-L. (American Institute of Physics, 2006-04-15)
      We have fabricated Fibonacci [Co/Pt] multilayers with two constituent Co/Pt bilayers, as well as periodic multilayers of the same Co/Pt bilayers, all of which exhibit perpendicular magnetic anisotropy. Magnetic properties ...
    • Condensation of magnons and spinons in a frustrated ladder 

      Fouet, J.-B.; Mila, F.; Clarke, D.; Youk, H.; Tchernyshyov, O.; Fendley, P.; Noack, R.M. (American Physical Society, 2006-06-01)
      Motivated by the ever-increasing experimental effort devoted to the properties of frustrated quantum magnets in a magnetic field, we present a careful and detailed theoretical analysis of a one-dimensional version of this ...
    • 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 ...
    • 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 ...
    • 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 ...
    • 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 ...
    • Wrinkling of a bilayer membrane 

      Concha, A.; McIver, J.W.; Mellado, P.; Clarke, D.; Tchernyshyov, O.; Leheny, R.L. (American Physical Society, 2007-01)
      The buckling of elastic bodies is a common phenomenon in the mechanics of solids. Wrinkling of membranes can often be interpreted as buckling under constraints that prohibit large-amplitude deformation. We present a ...
    • Asymmetric domain nucleation and unusual magnetization reversal in ultrathin Co films with perpendicular anisotropy 

      Iunin, Y.L.; Kabanov, Y.P.; Nikitenko, V.I.; Cheng, X.M.; Clarke, D.; Tretiakov, O.A.; Tchernyshyov, O.; Shapiro, A.J.; Shull, R.D.; Chien, C.L. (American Physical Society, 2007-03-16)
      We report unexpected phenomena during magnetization reversal in ultrathin Co films and Co/Pt multilayers with perpendicular anisotropy. Using magneto-optical Kerr microscopy and magnetic force microscopy we have observed ...
    • 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 ...
    • Stripes in thin ferromagnetic films with out-of-plane anisotropy 

      Clarke, D.; Tretiakov, O.A.; Tchernyshyov, O. (American Physical Society, 2007-05-01)
      We examine the T=0 phase diagram of a thin ferromagnetic film with a strong out-of-plane anisotropy (e.g., Co/Pt multilayers) in the vicinity of the reorientation phase transition. The phase diagram in the anisotropy-applied-field ...