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Seminarium MTPR - Prof. UAM dr hab. Maciej Wiesner

Electron-acoustic phonon interactions in intercalated topological insulators

Date: November 9, 2022, 13:00 – 14:00

Speaker: Prof. UAM dr hab. Maciej Wiesner (Faculty of Physics, Adam Mickiewicz University Poznań, Poland)

Charge and heat transport in the intercalated topological insulator (TI) Bi2Se3 shows that theoretical predictions modeling homogenous (not layered) materials can be applied to van der Waals (vdW) crystals in a limited way. Disorder-related small unit cell deformation of the topological insulator caused by intercalants enhances the separation of in-plane and cross-plane processes.

The disorder has also a significant effect on electron-phonon interactions (EPI). Electric conductivity measured in the TI showed the contribution of electron-electron (EEI) and electron-phonon interactions (EPI) to heat transport. The contribution was analyzed in temperature ranges determined by three temperatures: the Bloch-Grüneisen, the disorder-related temperature, and the 2D-3D phonon crossover temperature.

Shot noise measurements revealed that heat transport, due to EPI, in the layered material is more sensitive to an anisotropy related to layered structure than DC charge transport. In this presentation, I will show that the results of charge transport in TIs allow us to distinguish the electron-longitudinal phonon interaction from the electron-transversal phonon interaction.

Investigations of the discussed processes will be continued in other vdW materials in a newly established lab that allows for a change of temperature from 10mK to 30 K with a magnetic field from 0T to 12T turned on. This unique property will enable a precise tuning of phonons’ contribution to charge and heat transport as well as investigation of quantum interference phenomena as a function of temperature.