All-optical switching by domain wall motion has been obtained in Co/Pd superlattices with a TiS oscillator. Heat accumulation is part of the switching process for our experimental conditions. Numerical calculations point to a connection between domain wall motion and in-plane heat diffusion.
Pump-probe experiments and polarizing microscopy are applied to examine
temperature and heat flow in metallic magnetic superlattices on glass
substrates. A model of heat diffusion in thin layers for cylindrical symmetry,
equivalent to the Green's function method, gives a good description of the
results. The frequency dependence of temperature modulation shows that a glass
layer should be added to the sample structure. The demagnetization patterns are
reproduced with a Green's function that includes an interface conductance.Comment: 9 pages, 7 figure
Time-resolved pump-probe measurements were made at variable heat accumulation in Co/Pd superlattices. Heat accumulation increases the baseline temperature and decreases the equilibrium magnetization. Transient ultrafast demagnetization first develops with higher fluence in parallel with strong equilibrium thermal spin fluctuations. The ultrafast demagnetization is then gradually removed as the equilibrium temperature approaches the Curie temperature. The transient magnetization time-dependence is well fit with the spin-flip scattering model.
Time-resolved pump-probe measurements show ultrafast and heat accumulation demagnetization in Co/Pd superlattices on glass substrates. A model of demagnetizing fields and micromagnetic simulations are applied to examine the evolution of a demagnetized cylinder into a switched state.
A delay modulator, made of glass plates rotating in a pump beam, is applied to measure time-resolved rates of transient processes in a pump-probe experimental setup. Glass plates modulate both delay and beam power. The contribution from the power modulation is subtracted by using a scaled-down measurement made with metal chopper blades. Delay modulation results obtained with this procedure are consistent with the derivative in delay of the usual power modulation and can show a larger signal to noise ratio.
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