Dynamics of the laser-induced ferroelectric excitation in BaTiO_3 studied by x-ray diffraction

摘要

Ultrafast time resolved x-ray powder scattering is used to reveal the structural dynamics in BaTiO_3 powder excited by femtosecond laser pulses. The lattice excitation close to the Curie point of BaTiO_3 is analyzed by refining the powder pattern (Rietveld method) to obtain the lattice state and the atomic positions. It is found that the tetragonal distortion of the ferroelectric phase is diminished within the 100 ps time resolution of the experiment. The unit cell polarization, however, is not affected by this excitation, evidenced by the preserved Ti and oxygen displacement. The change in splitting relaxes on the nanosecond time scale.