Now showing items 42-58 of 58

    • 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 ...
    • Quasi-Langmuir-Blodgett thin film deposition of carbon nanotubes 

      Gruner, G.; Gabriel, J.-C. P.; Armitage, N.P. (American Institute of Physics, 2004-03-15)
      The handling and manipulation of carbon nanotubes continues to be a challenge to those interested in the application potential of these promising materials. To this end, we have developed a method to deposit pure nonoriented ...
    • 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 ...
    • 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 ...
    • 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 ...
    • 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 ...
    • 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 ...
    • A strongly fluctuating quasi-two-dimensional insulator 

      Cooper, A.S.; Espinosa, G.P.; Broholm, C.; Aeppli, G. (American Institute of Physics, 1991-04-15)
      The authors describe neutron-scattering data for SrCr8-xGa4+xO19, a layered compound containing planes of S=3/2 Cr3+ ions which form Kagome lattices. Despite strong antiferromagnetic interactions (θCW≈-500 K), fluctuations ...
    • Studies of deposition order anomaly of exchange coupling in bilayers and trilayers of NiFe and CoO 

      Ambrose, T.; Leifer, K.; Hemker, K.J.; Chien, C.-L.; Ambrose, T.1; Leifer, K.; Hemker, K.J.; Chien, C.L. (American Institute of Physics, 1997-04-15)
      The temperature dependence of the exchange field and coercivity and the effect of deposition order have been studied in a series of bilayer (NiFe/CoO and CoO/NiFe) and trilayer (NiFe/CoO/NiFe) films. A profound difference ...
    • Synthesis of Mn-Zn ferrite from Na2O-B2O3 flux under CO-CO2 ambients 

      Plaskett, T.S.; Shivashankar, S.A.; Gilbert, B.L.; Olson, B.L.; Chien, C.-L.; Herman, D.A. Jr. (American Institute of Physics, 1982-03)
      Synthesis was carried out by dissolving MnO, ZnO, and Fe2O3 in the molar ratio 0.42:0.44:1.07 in fluxes of Na2O:xB2O3 at 900 °C and slow cooling under ambients of CO-CO2 mixtures; x varied from 1.34 to 2.0 and Co-Co2 from ...
    • 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), ...
    • 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 ...