P. Maly

Laser-Induced Precession of Magnetization in GaMnAs

We report on the photo-induced precession of the ferromagnetically coupled Mn spins in (Ga,Mn)As, which is observed even with no external magnetic field applied. We concentrate on various experimental aspects of the time-resolved magneto-optical Kerr effect (TR-MOKE) technique that can be used to clarify the origin of the detected signals. We show that the measured data typically consist of several different contributions, among which only the oscillatory signal is directly connected with the ferromagnetic order in the sample.

Negative and positive nonlinear absorption in CdS-doped glasses

. Weinvestigated photodarkend samples, which were exposed to pump light for a long time(about 1 h). Fig.1The optical transmission spectra of the samples studied are shown in Fig. 1. All thesamples are doped by CdS, and different positions of the absorption edge are due tothe different nanocrystal sizes (effect of quantum confinement). We observed negative2

Ultrafast Carrier Dynamics in CdSSe Nanocrystals in Glass Matrix

We report on photoexcited carrier dynamics in CdSSe nanocrystals in a glass matrix studied by ultrafast photoluminescence spectroscopy. The results of photoluminescence up-conversion measurements are compared with those of transient absorption and degenerate four-wave mixing (DFWM) experiments. The fast component (about 1 ps) of the photoluminescence and transient absorption decay is attributed to hole trapping in a surface state.

Ultrafast carrier dynamics in CdS-doped glasses

Luminescence dynamics of CdS-doped glasses were measured using up-conversion technique, and they were compared with transmission dynamics. An analysis of the decay curves of luminescence and transmission dynamics has been performed using a multi-exponential fit. Although slower decay component is large in transmission dynamics, it is negligibly small in luminescence dynamics. This difference is observed in all samples investigated, and this may be caused by the difference in relaxation paths of electrons and holes in CdS nanocrystals. Effect of induced absorption on transmission dynamics was examined.

Ultrafast carrier transport in silicon nanocrystal superlattices

Time-resolved terahertz spectroscopy is employed to study silicon nanocrystals prepared by thermal decomposition of silicon-rich SiOx layers. We observe that higher silicon content favors formation of larger silicon clusters with short-range percolation.