Dresden 2026 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
O: Fachverband Oberflächenphysik
O 14: Ultrafast electron dynamics at surface and interfaces I
O 14.6: Talk
Monday, March 9, 2026, 16:30–16:45, TRE/MATH
Interplay between intraband acceleration and interband excitation in Bi2Te3 by subcycle time-resolved THz-ARPES — •Tim Bergmeier1,2, Suguru Ito1, Jens Güdde1, and Ulrich Höfer2 — 1Fachbereich Physik, Philipps-Universität Marburg, Germany — 2Fachbereich Physik, Universität Regensburg, Germany
Angle-resolved photoemission spectroscopy (ARPES) using THz driving fields with subcycle temporal resolution offers unique capabilities to investigate the dynamics of lateral Dirac currents in the surface state of topological insulators. Whereas low THz-frequencies result in pure intraband accelerations within the surface state [1], additional interband excitations become possible at higher frequencies [2,3].
Here, we present subcycle-resolved THz-ARPES measurements with 2D momentum imaging resolving the full Dirac cone of Bi2Te3. For this purpose, we generate frequency-tunable two-cycle MIR pulses (20-40 THz) with electric field strengths up to MV/cm at the sample surface, combined with an ultrashort 400 nm two-photon probe (<15 fs), at a repetition rate of 200 kHz. For a frequency of 25 THz, we show that the momentum distribution of the field-driven intraband acceleration is strongly influenced by the Dirac cones hexagonal warping, while being superimposed with resonant interband excitations that are only possible in the materials Γ M direction.
[1] J. Reimann et al., Nature 562, 396 (2018).
[2] S. Ito et al., Nature 616, 696 (2023).
[3] C.P. Schmid et al., Nature 593, 385 (2021).
Keywords: ARPES; Subcycle; THz; Topological insulator; Ultrafast