Now showing items 14-33 of 58

    • 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 ...
    • 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 ...
    • 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. ...
    • Dynamics of a vortex domain wall in a magnetic nanostrip: application of the collective-coordinate approach 

      Clarke, D.J.; Tretiakov, O.A.; Chern, G.-W.; Bazaliy, Ya.B.; Tchernyshyov, O. (American Physical Society, 2008-10-01)
      The motion of a vortex domain wall in a ferromagnetic strip of submicron width under the influence of an external magnetic field exhibits three distinct dynamical regimes. In a viscous regime at low fields the wall moves ...
    • Dynamics of domain walls in magnetic nanostrips 

      Tretiakov, O.A.; Clarke, D.; Chern, G.-W.; Bazaliy, Ya.B.; Tchernyshyov, O. (American Physical Society, 2008-03-28)
      We express the dynamics of domain walls in ferromagnetic nanowires in terms of collective coordinates, generalizing Thiele[psila]s steady-state results. For weak external perturbations the dynamics is dominated by a few ...
    • Effect of spacer material on the magnetic surface anisotropy in ultrathin Fe70B30 multilayer films 

      Hicken, R.J.; Rado, G.T.; Chien, C.-L. (American Institute of Physics, 1991-04-15)
      It has been found recently that the magnetic surface anisotropy Ks in Fe70B30/Ag multilayer films decreases monotonically with magnetic layer thickness (2L) for 2L<16.5 Å. In order to determine possible effects of the ...
    • Effects of carrier mobility and morphology in organic semiconductor spin valves 

      Liu, Yaohua; Lee, Taegweo; Katz, Howard E.; Reich, Daniel H. (American Institute of Physics, 2009-05-01)
      We studied spin transport in four organic semiconductors (OSCs) with different electronic properties. Magnetoresistance (MR) effects were observed up to room temperature in junctions based on an electron-carrying OSC, ...
    • 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 ...
    • Exchange coupling between Cr and ferromagnetic thin films 

      Yang, F.Y.; Chien, C.-L. (American Institute of Physics, 2003-05-15)
      Exchange bias has been observed in Ni81Fe19/Cr bilayers. The exchange bias field for Cr thickness tCr larger than 62 Å increases with tCr and levels off at tCr=150 Å, whereas coercivity increases without saturation. The ...
    • Exploiting finite size effects in a novel core/shell microstructure 

      Liu, Zhu; Xia, Guoqiang; Zhu, Frank; Kim, Su; Markovic, Nina; Chien, Chia-Ling; Searson, Peter C. (American Institute of Physics, 2008-03-15)
      Electrodeposition of Ni-Cu alloys at high Cu(II) concentration and large overpotentials results in phase separation with a unique microstructure characterized by features with a copper-rich core and a nickel-rich shell. ...
    • 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 ...
    • Giant positive magnetoresistance of Bi nanowire arrays in high magnetic fields 

      Hong, Kimin; Yang, F.Y.; Liu, Kai; Reich, D.H.; Searson, P.C.; Chien, C.-L.; Balakirev, F.F.; Boebinger, G.S. (American Institute of Physics, 1999-04-15)
      We have studied the magnetoresistance of electrodeposited Bi wires with diameters between 200 nm and 2 μm in magnetic fields up to B=55 T. In zero field, the resistance increases with decreasing temperature, indicating ...
    • 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 ...
    • Ising phases of Heisenberg ladders in a magnetic field 

      Penc, K.; Fouet, J.-B.; Miyahara, S.; Tchernyshyov, O.; Mila, F. (American Physical Society, 2007-09-14)
      We show that Dzyaloshinskii-Moriya (DM) interactions can substantially modify the phase diagram of spin-1/2 Heisenberg ladders in a magnetic field provided they compete with exchange. For nonfrustrated ladders, they induce ...
    • 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 core loss of ultrahigh strength FeCo alloys 

      Cheng, X.M.; Zhang, X.K.; Zhang, D.Z.; Lee, S.H.; Duckham, A.; Weihs, T.P.; Cammarata, R.C.; Chien, C.-L. (American Institute of Physics, 2003-05-15)
      Hiperco® 50 alloy heat treated between 450 and 650°C exhibits superior mechanical properties. We report the measurements of the ac core loss at various frequencies up to 4500 Hz of the Hiperco® 50 alloy samples annealed ...