Current-induced domain wall motion including thermal effects based on Landau-Lifshitz-Bloch equation
2009, Schieback, Christine, Hinzke, Denise, Kläui, Mathias, Nowak, Ulrich, Nielaba, Peter
We employ the Landau-Lifshitz-Bloch (LLB) equation to investigate current-induced domain wall motion at finite temperatures by numerical micromagnetic simulations. We extend the LLB equation with spin torque terms that account for the effect of spin-polarized currents and we find that the velocities depend strongly on the interplay between adiabatic and non-adiabatic spin torque terms. As a function of temperature, we find non-monotonous behavior, which might be useful to determine the relative strengths of the spin torque terms experimentally.
Laser induced magnetization switching in films with perpendicular anisotropy : a comparison between measurements and a multi-macrospin model
2009, Bunce, Christopher, Wu, Jing, Ju, Ganping, Lu, Bin, Hinzke, Denise, Kazantseva, Natalia, Nowak, Ulrich, Chantrell, Roy W.
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/cm2 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.