Results

I am very proud to show our most recent achievement on the IDK laboratory: Single-shot amorphization on phase-change nanoparticles. This work, with first author PhD Barbara Casarin, demonstrates for the first time that the switching process of phase-change nanoparticles -a crystal-to-amorphous reversible transition- is more efficient than in thin films. In the article you will not only find the accurate method used to investigate the process but also the underlying physics.

First experiments:

Here below a plot of the demagnetization dynamics in Fe₂₀Ni₈₀ film.

The experiment is performed in longitudinal MOKE configuration, probing at 400 nm and exciting at 800 nm. Time resolution is approximately 100 fs. Magneto-optical experiments exploit the Faraday and the Kerr effects, where the polarisation state of the probe is sensible to the magnetisation component along the light k-vector. As shown above, it is thus possible to estimate the exact direction (in this case in-plane) and absolute value (-25%) of the sample magnetisation.

Other tests on Pr_0.5Ca_1.5MnO₄:

In order to measure both the electric field amplitude and direction of the probe pulse, MOKE and Faraday experiments are performed via a balanced photo-detection scheme. Such detection scheme is actually useful to study any material anisotropy, like twin domains, crystal birefringence, structural distortions or charge-orbital-ordering. Here below we show the reflectivity and birefringence dynamics in PCMO: interestingly, while the first (DR/R) shows clear signatures of a (photo-induced) insulator-to-metal transition, the second reports the nearly instantaneous destruction of the charge-orbital-ordering state.