Super-resolution lightwave tomography of electronic bands in quantum materials – Publication by B4

A light flash (yellow) induces the movement of electrons in the band structure (red curve) resulting in the formation of localized electronic interference combs (peaks). The emitted radiation (red) enables the analysis of the electronic band structure. © Markus Borsch, University of Michigan, USA. Reprinted with permission from AAAS.

Stacking of two-dimensional (2D) materials yield promising properties for the development of new devices with outstanding functionality. However, detailed knowledge of the electronic structure is necessary to tailor their properties. Within the cooperation of Prof. Huber (Uni Regensburg), Prof. Kira (Uni Michigan) and Prof. Koch (Uni Marburg, project B4), a new method was developed enabling the reconstruction of the band structure of 2D materials.

The quantum material WSe₂ was simultaneously excited by two laser pulses in the visible range and in the THz spectral range. The resonant excitation of the weak optical pulse and simultaneous irradiation with a strong THz pulse result in harmonic sideband generation (HSG) in the transmitted spectrum. Due to the wave-particle dualism of electrons, electronic interference combs evolve in momentum space (cf. Figure on the left). By analyzing multiple sideband spectra at different THz frequencies and intensities, it is possible to reconstruct the band structure with super-resolution.

This concept offers an all-optical and practical approach for a three-dimensional tomography of the electronic structure of small quantum materials as shown for WSe2. This work is a great extend to the research in the SFB as it provides the possibility to examine the electronic band structure of 2D materials, such as TMDCs, even under ambient conditions.

Contact

Prof. Dr. Stephan W. Koch
Philipps-Universität Marburg
Department of Physics, Theoretical Semiconductor Physics
Renthof 5, 35032 Marburg
Tel.: 06421 28-21336
EMAIL