Surface photovoltage dynamics at passivated silicon surfaces: influence of substrate doping and surface termination.

We have monitored the temporal evolution of the band bending at controlled silicon surfaces after a fs laser pump excitation. Time-resolved surface photo-voltage (SPV) experiments were performed using time resolved photoemission spectroscopy with time resolution of about 30 ns. To disentangle the influence of doping and surface termination on SPV dynamics, we compare the results obtained on two surface terminations: the water saturated (H,OH)-Si(001) surface and the thermally oxidized Si(001) one.

Spin/valley pumping of resident electrons in WSe and WS monolayers.

Monolayers of transition metal dichalcogenides are ideal materials to control both spin and valley degrees of freedom either electrically or optically. Nevertheless, optical excitation mostly generates excitons species with inherently short lifetime and spin/valley relaxation time. Here we demonstrate a very efficient spin/valley optical pumping of resident electrons in n-doped WSe and WS monolayers.

Subpicosecond metamagnetic phase transition in FeRh driven by non-equilibrium electron dynamics.

Femtosecond light-induced phase transitions between different macroscopic orders provide the possibility to tune the functional properties of condensed matter on ultrafast timescales. In first-order phase transitions, transient non-equilibrium phases and inherent phase coexistence often preclude non-ambiguous detection of transition precursors and their temporal onset. Here, we present a study combining time-resolved photoelectron spectroscopy and ab-initio electron dynamics calculations elucidating the transient subpicosecond processes governing the photoinduced generation of ferromagnetic order in antiferromagnetic FeRh.

Unraveling intrinsic correlation effects with angle-resolved photoemission spectroscopy.

Interaction effects can change materials properties in intriguing ways, and they have, in general, a huge impact on electronic spectra. In particular, satellites in photoemission spectra are pure many-body effects, and their study is of increasing interest in both experiment and theory. However, the intrinsic spectral function is only a part of a measured spectrum, and it is notoriously difficult to extract this information, even for simple metals.