Ultrafast Dynamics of Interface Currents
For many existing electronic devices based on thin films and even more so for novel device concepts based on interface electronic states, the charge transfer parallel to the interface plays a crucial role. Within the framework of this project, we apply experimental techniques originally developed for the study of surface currents to investigate lateral electrical currents at internal interfaces in a contact-free fashion and with femtosecond time resolution.
The interface currents are either be excited optically by means of coherent control schemes or by accelerating the electrons with the electric field of strong THz transients. The observation of the current dynamics by time- and angle-resolved photoemission spectroscopy (tr-ARPES) in the full two-dimensional k-space allows us to study the effect of inelastic and elastic momentum scattering at the interface on current transport. We extend previous work on Dirac currents of topological insulators and embed the topological surface state under thin protecting layers for device applications. In parallel, we investigate the effect of interfaces on the decay of photocurrents induced in graphene and graphene-related materials as well as in two dimensional semiconductors such as GaS and InSe.
- J. Güdde. U. Höfer
Ultrafast dynamics of photocurrents in surface states of topological insulators
Phys. Stat. Sol. B 257 (2020), – Feature Article.
- K. Sumida, M. Kakoki, J. Reimann, M. Nurmamat, S. Goto, Y. Takeda, Y. Saitoh, K.A. Kokh, O. E. Tereshchenko, J. Güdde, U. Höfer, A. Kimura
Magnetic-impurity-induced modifications to ultrafast carrier dynamics in the ferromagnetic topological insulators Sb2-xVxTe3
New J. Phys. 21, 1376 (2019).
- J. Reimann, S. Schlauderer, C.P. Schmid, F. Langer, S. Baierl, K.A. Kokh, O.E. Tereshchenko, A. Kimura, C. Lange, J. Güdde, U. Höfer, R. Huber
Subcycle observation of lightwave-driven Dirac currents in a topological surface band
Nature 562, 396 (2018).
- K. Kuroda, J. Reimann, K.A. Kokh, O.E. Tereshchenko, A. Kimura, J. Güdde, U. Höfer
Ultrafast energy- and momentum-resolved surface Dirac photocurrents in the topological insulator Sb2Te3
Phys. Rev. B 95, 081103(R) (2017).