Now showing items 1-20 of 57

  • Anisotropy, damping and coherence of magnetization dynamics in a 10 µm square Ni81Fe19 element 

    Barman, A.; Kruglyak, V.V.; Hicken, R.J.; Kundrotaite, A.; Rahman, M. (American Institute of Physics, 2003)
    We have studied magnetization precession in a square Ni81Fe19 element, of 10 μm width, by time-resolved scanning Kerr effect microscopy. From the frequency of precession, we deduce a fourfold in-plane anisotropy of about ...
  • Characterization of spin-valves fabricated on opaque substrates by optical ferromagnetic resonance 

    Barman, A.; Kruglyak, V.V.; Hicken, R.J.; Marrows, C.H.; Ali, M.; Hindmarch, A.T.; Hickey, B.J. (American Institute of Physics, 2002)
    We have used a transmission line deposited on a transparent substrate to deliver an optically triggered magnetic field pulse to a spin valve structure deposited upon an opaque substrate. The ensuing ferromagnetic resonance ...
  • Continuous evolution of the in-plane magnetic anisotropies with thickness in epitaxial Fe films 

    Gester, M.; Daboo, C.; Hicken, R.J.; Gray, S.J.; Ercole, A.; Bland, J.A.C. (American Institute of Physics, 1996)
    We have studied the evolution of the magnetic in‐plane anisotropy in epitaxial Fe/GaAs films of both (001) and (110) orientation as a function of the Fe layer thickness using the longitudinal magneto‐optic Kerr effect and ...
  • Crystallization of Ge2Sb2Te5 films by amplified femtosecond optical pulses 

    Liu, Y.; Aziz, Mustafa M.; Shalini, Ashawaraya; Wright, C. David; Hicken, R.J. (American Institute of Physics, 2012)
    The phase transition between the amorphous and crystalline states of Ge2Sb2Te5 has been studied by exposure of thin films to series of 60 femtosecond (fs) amplified laser pulses. The analysis of microscope images of marks ...
  • Dataset of Observation of T2-like coherent optical phonons in epitaxial Ge2Sb2Te5/GaSb(001) films 

    Shalini, Ashawaraya; Liu, Y.; Al-Jarah, Uday Ali Sabeeh; Srivastava, G.P.; Wright, C. David; Katmis, F.; Braun, W.; Hicken, R.J. (University of Exeter, 2013-10-04)
    The phonon spectrum of Ge2Sb2Te5 is a signature of its crystallographic structure and underlies the phase transition process used in memory applications. Epitaxial materials allow coherent optical phonons to be studied in ...
  • Dependence of anisotropy and damping on shape and aspect ratio in micron sized Ni 81Fe 19 elements 

    Barman, A.; Kruglyak, V.V.; Hicken, R.J.; Scott, J.; Kundrotaite, A.; Rahman, M. (American Institute of Physics, 2004)
    We have studied magnetic anisotropy and damping in Ni81Fe19 elements of different shape and aspect ratio by time-resolved scanning Kerr effect microscopy and micromagnetic simulations. Square elements show a fourfold ...
  • Dependence of spatial coherence of coherent suppression of magnetization precession upon aspect ratio in Ni 81Fe 19 microdots 

    Barman, A.; Kruglyak, V.V.; Hicken, R.J.; Scott, J.; Rahman, M. (American Institute of Physics, 2005)
    Coherent suppression of magnetization dynamics in circular microdots of Ni81Fe19 has been observed by time-resolved scanning Kerr effect microscopy. The applied pulsed field rose sharply, stimulating precession, and then ...
  • Determination of the Thickness of Al2O3 Barriers in Magnetic Tunnel Junctions 

    Buchanan, J.D.R.; Hase, T.P.A.; Tanner, B.K.; Hughes, N.D.; Hicken, R.J. (American Institute of Physics, 2002)
    The barrier thickness in magnetic spin-dependent tunnel junctions with Al2O3 barriers has been measured using grazing incidence x-ray reflectivity and by fitting the tunneling current to the Simmons model. We have studied ...
  • Domain-wall pinning, nonadiabatic spin-transfer torque, and spin-current polarization in permalloy wires doped with vanadium 

    Lepadatu, S.; Claydon, J.S.; Kinane, C.J.; Charlton, T.R.; Langridge, Sean; Potenza, A.; Dhesi, Sarnjeet S.; Keatley, Paul Steven; Hicken, R.J.; Hickey, B.J.; Marrows, C.H. (American Physical Society, 2010)
    Using pulsed-current measurements we investigate the domain-wall depinning via spin-transfer torque from pinning potentials in V-doped Ni80Fe20 wires. The domain-wall depinning boundary, showing the variation of threshold ...
  • Dynamic configurational anisotropy in nanomagnets 

    Kruglyak, V.V.; Keatley, Paul Steven; Hicken, R.J.; Childress, J.R.; Katine, J.A. (American Physical Society, 2007)
    The angular dependence of ultrafast magnetization dynamics in nanomagnets of square shape was studied by magneto-optical pump-probe measurements. In agreement with micromagnetic simulations, both the number of precessional ...
  • Evidence for hot electron magnetocurrent in a double barrier tunnel junction device 

    Ladak, S.; Hicken, R.J. (2005)
    Hot electron transport has been studied in three terminal Ta/TaOx/Co/AlOx/Ni81Fe19 structures fabricated by magnetron sputtering through shadow masks. With the Co base and Ta collector connected together via a small resistor, ...
  • Evidence of a barrier oxidation dependence on the interfacial magnetism in Co/alumina based magnetic tunnel junctions 

    Telling, N.D.; van der Laan, Gerrit; Ladak, S.; Hicken, R.J.; Arenholz, E. (American Institute of Physics, 2006)
    Soft x-ray absorption spectroscopy and magnetic circular dichroism at the Co L-2,L-3 edge have been applied to explore the near-interfacial magnetism of Co electrodes in Co/alumina based magnetic tunnel junctions. By taking ...
  • Evidence of local moment formation in Co-based Heusler alloys 

    Telling, N.D.; Keatley, Paul Steven; van der Laan, Gerrit; Hicken, R.J.; Arenholz, E.; Sakuraba, Y.; Oogane, M.; Ando, Y.; Takanashi, K.; Sakuma, A.; Miyazaki, T. (American Physical Society, 2008)
    We examine the formation of local moments in Heusler alloys of the composition Co(2)MnZ (where Z=Si or Al) using the combined techniques of x-ray magnetic circular and linear dichroism. The existence of local moments in ...
  • Excitation and Imaging of Precessional Modes in Soft-Magnetic Squares 

    Neudert, A.; Keatley, Paul Steven; Kruglyak, V.V.; McCord, Jeffrey; Hicken, R.J. (Institute of Electrical and Electronics Engineers (IEEE), 2008)
    We investigated the high-frequency modes of 40 mum wide, 160 nm thick Fe 70Co8B12Si10 squares using time-resolved scanning Kerr microscopy. Two modes were identified using pulsed field excitation while the spatial character ...
  • Excitation of propagating spin waves with global uniform microwave fields 

    Au, Y.; Davison, T.; Ahmad, E.; Keatley, Paul Steven; Hicken, R.J.; Kruglyak, V.V. (American Institute of Physics, 2011)
    We demonstrate a magnonic architecture that converts global free-space uniform microwaves into spin waves propagating in a stripe magnonic waveguide. The architecture is based upon dispersion mismatch between the narrow ...
  • Ferrite-filled cavities for compact planar resonators 

    Keatley, Paul Steven; Durrant, C.J.; Berry, S.J.; Sirotkin, Evgeny; Hibbins, Alastair P.; Hicken, R.J. (American Institute of Physics (AIP) -, 2014)
    Sub-wavelength metallic planar cavities, closed at one end, have been constructed by wrapping aluminium foil around teflon or ferrite slabs. Finite cavity width perturbs the fundamental cavity mode frequency of ferrite-filled ...
  • Heavily loaded ferrite-polymer composites to produce high refractive index materials at centimetre wavelengths 

    Parke, L.; Hooper, Ian R.; Hicken, R.J.; Dancer, C.E.J.; Grant, P.S.; Youngs, I.J.; Sambles, J. Roy; Hibbins, Alastair P. (American Institute of Physics (AIP), 2013)
    A cold-pressing technique has been developed for fabricating composites composed of a polytetrafluoroethylene-polymer matrix and a wide range of volume-fractions of MnZn-ferrite filler (0%–80%). The electromagnetic properties ...
  • Imaging collective magnonic modes in 2D arrays of magnetic nanoelements 

    Kruglyak, V.V.; Keatley, Paul Steven; Neudert, A.; Hicken, R.J.; Childress, J.R.; Katine, J.A. (American Physical Society, 2010)
    We have used time resolved scanning Kerr microscopy to image collective spin wave modes within a 2D array of magnetic nanoelements. Long wavelength spin waves are confined within the array as if it was a continuous element ...
  • Imaging small-amplitude magnetization dynamics in a longitudinally magnetized microwire 

    Kruglyak, V.V.; Keatley, Paul Steven; Neudert, A.; Delchini, M.; Hicken, R.J.; Childress, J.R.; Katine, J.A. (American Physical Society, 2008)
    We have used time-resolved scanning Kerr microscopy to study spin waves in a magnetic microwire subjected to a bias magnetic field applied parallel to its long axis. The spin-wave spectra obtained from different points ...
  • Imaging the dephasing of spin wave modes in a square thin film magnetic element 

    Barman, A.; Kruglyak, V.V.; Hicken, R.J.; Rowe, J.M.; Kundrotaite, A.; Scott, J.; Rahman, M. (American Physical Society, 2004)
    We have used time-resolved scanning Kerr effect microscopy to study dephasing of spin wave modes in a square Ni81Fe19 element of 10 μm width and 150 nm thickness. When a static magnetic field H was applied parallel to an ...