Steady-state thermal gradient induced by pulsed laser excitation in a ferromagnetic layer Steady-state thermal gradient induced by pulsed laser excitation in a ferromagnetic layer

S Shihab (1, 2) , L. Thevenard (1, 2) , Aristide Lemaître (3) , J.-y Duquesne (4, 1) , C. Gourdon (2, 1)

1 INSP - Institut des Nanosciences de Paris
2 INSP-E1 - Nanostructures et systèmes quantiques
3 LPN - Laboratoire de photonique et de nanostructures
4 INSP-E3 - Acoustique pour les nanosciences

In all-optical pump-probe experiments on ferromagnetic layers, the determination of the temperature under the pump laser spot is crucial for a quantitative modeling of the magnetization dynamics. We present here a method to quantify this thermal gradient, exemplified on a (Ga, Mn)(As, P) ferromagnetic semiconductor layer on a GaAs substrate. To estimate the local steady-state temperature, we use the coercive field as a thermometer. The probe records the hysteresis cycle spatially across the hot spot, using the magnetic linear birefringence/dichroism of the sample. Our results are analyzed using the heat diffusion equation with two fitting parameters, the thermal conductivity of the layer/substrate sample and the thermal resistance between the substrate and the thermostat. This opens the way to a quantitative modeling of laser pulse-triggered magnetization dynamics in the presence oftransient temperature effects.

Domaines: Science des matériaux [cond-mat.mtrl-sci]

S Shihab, L. Thevenard, Aristide Lemaître, J.-y Duquesne, C. Gourdon. Steady-state thermal gradient induced by pulsed laser excitation in a ferromagnetic layer Steady-state thermal gradient induced by pulsed laser excitation in a ferromagnetic layer. Journal of Applied Physics, 2016, 119 (15), pp.153904. ⟨10.1063/1.4947226⟩. ⟨hal-01438597⟩