Now showing items 36-55 of 58

    • Magnetic properties of epitaxial Mn-doped ZnO thin films 

      Cheng, X.M.; Chien, C.-L. (American Institute of Physics, 2003-05-15)
      Epitaxial ZnO thin films doped with 7% Mn have been made by reactive rf magnetron sputtering onto (112_0) sapphire substrates at 400°C. X-ray diffraction measurements reveal that the Zn0.93Mn0.07O film has a (0001) wurtzite ...
    • 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 ...
    • 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 ...
    • Memory effects of exchange coupling in CoO/Ni81Fe19 bilayers 

      Gokemeijer, N.J.; Chien, C.-L. (American Institute of Physics, 1999-04-15)
      By changing the field-cooling procedure, the value and even the sign of the exchange field HE in CoO/Ni81Fe19 bilayers can be greatly altered. The value of HE can be made to vanish at any temperature below TN. We also show ...
    • 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 ...
    • 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 ...