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arXiv · 2212.07532

Two-dimensional THz spectroscopy of nonlinear phononics in the topological insulator $\mathrm{MnBi}_2\mathrm{Te}_4$

T. G. H. Blank·K. A. Grishunin·K. A. Zvezdin·N. T. Hai·J. C. Wu·S. -H. Su·J. -C. A. Huang·A. K. Zvezdin·A. V. Kimel
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Abstract

The interaction of a single-cycle THz electric field with the topological insulator $\mathrm{MnBi}_2\mathrm{Te}_4$ triggers strongly anharmonic lattice dynamics, promoting fully coherent energy transfer between the otherwise non-interacting Raman-active $E_g$ and infrared (IR)-active $E_u$ phononic modes. Two-dimensional (2D) THz spectroscopy combined with modeling based on the classical equations of motion and symmetry analysis reveals the multi-stage process underlying the excitation of the Raman-active $E_g$ phonon. In this process, the THz electric field first prepares a coherent IR-active $E_u$ phononic state and subsequently interacts with this state to efficiently excite the $E_g$ phonon.

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T. G. H. Blank, K. A. Grishunin, K. A. Zvezdin, N. T. Hai, J. C. Wu, S. -H. Su, J. -C. A. Huang, A. K. Zvezdin, A. V. Kimel. 2022-12-14. Two-dimensional THz spectroscopy of nonlinear phononics in the topological insulator $\mathrm{MnBi}_2\mathrm{Te}_4$. https://doi.org/10.1103/physrevlett.131.026902

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