Evolution of picosecond surface electric fields generated by photon-induced charge emission from La_0.67Sr_0.33MnO₃ thin films at 300 K and 77 K

The spatial-temporal distribution of picosecond surface electric fields, associated with the femtosecond-laser-induced photoemission from La_0.67Sr_0.33MnO₃ (LSMO) single crystal thin films, at 300 K and 77 K, were interrogated by sub-picosecond, 30 keV, electron pulses and reconstructed by a “three-layer” theoretical model. Around a few tens of picoseconds after femtosecond laser illumination, a surprisingly strong surface electric field on the order of hundreds kV/m was observed on the LSMO film at room temperature. This electric field strength is on the same order as the field(s) used for altering the orbital domains in lanthanum strontium manganite films. The experimental data of this study imply that the self-induced transient electric fields, generated during photoemission, may be a promising means for the control of ultrafast processes in materials that are mainly achievable through strong THz excitations.