C. Bunce

Publications (3)3.53 Total impact

• Article: Damping in magnetization dynamics of single-crystal Fe3O4/GaN thin films

  X. Zou, J. Wu, P. K. J. Wong, Y. B. Xu, R. Zhang, Y. Zhai, C. Bunce, R. W. Chantrell
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  ABSTRACT: The time-resolved magnetization dynamics of epitaxial Fe3O4 thin films grown on GaN(100) was studied using a field pumped time-resolved magneto-optical Kerr (TRMOKE) setup. The dynamic responses of the magnetization in the 3 and 6 nm Fe3O4/GaN films under a 1 kOe magnetic field pulse were measured and compared to a macrospin Landau−Lifshitz−Gilbert (LLG) simulation. The anisotropy constants of the two systems have been estimated and the damping constant has been extracted by applying different bias field along two orthogonal directions. This work provides a first TRMOKE study of thickness and frequency dependence of damping in single crystal Fe3O4/GaN systems.
  Journal of Applied Physics 04/2011; 109(7):07D341-07D341-3. · 2.17 Impact Factor
• Source

  Available from: Roy W. Chantrell

  Article: Laser induced magnetization switching in films with perpendicular anisotropy: a comparison between measurements and a multi-macrospin model

  C. Bunce, J Wu, G. Ju, B Lu, D. Hinzke, N. Kazantseva, U. Nowak, R.W. Chantrell
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  ABSTRACT: Thermally-assisted ultra-fast magnetization reversal in a DC magnetic field for magnetic multilayer thin films with perpendicular anisotropy has been investigated in the time domain using femtosecond laser heating. The experiment is set-up as an optically pumped stroboscopic Time Resolved Magneto-Optical Kerr Effect magnetometer. It is observed that a modest laser fluence of about 0.3 mJ/square-cm induces switching of the magnetization in an applied field much less than the DC coercivity (0.8 T) on the sub-nanosecond time-scale. This switching was thermally-assisted by the energy from the femtosecond pump-pulse. The experimental results are compared with a model based on the Landau Lifschitz Bloch equation. The comparison supports a description of the reversal process as an ultra-fast demagnetization and partial recovery followed by slower thermally activated switching due to the spin system remaining at an elevated temperature after the heating pulse. Comment: 8 pages, 10 figures, to be submitted to PRB
  06/2009;
• Article: Picosecond Magnetization Dynamics of Single-Crystal Fe O Thin Films

  C. Bunce, J. Wu, Y.X. Lu, Y.B. Xu, R.W. Chantrell
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  ABSTRACT: The time-resolved magnetization dynamics of epitaxial Fe ₃O ₄ ultra-thin films grown on GaAs were investigated for the first time using a field pumped TRMOKE (time-resolved magneto-optical Kerr effect) setup. The dynamic response of the sample to the field pulse was measured for different DC bias fields applied along two orthogonal crystalline directions for 3 and 6 nm films. The results show a heavily damped precessional response to the applied field pulses. By fitting the Landau-Lifshitz-Gilbert equation to the data the temporal evolution of the magnetisation can be reproduced and the damping constant determined to be around 0.1.
  IEEE Transactions on Magnetics 12/2008; · 1.36 Impact Factor