Presentation Information
[7p-N205-1][JSAP-Optica Joint Symposia Invited Talk] Driving Electronic Structure Changes in 2D semiconductors with intense excitonic fields
〇Keshav Dani1 (1.Okinawa Inst. of Science and Technology)
Keywords:
2D semiconductors,time-resolved ARPES,excitons
In the 1930s, Frenkel and Wannier postulated the existence of an exciton – a bound electron-hole pair, to explain the unexpected presence of an absorptive neutral state in the forbidden bandgap region of a semiconductor. Since then, excitons have proved to play a vital role in our understanding of the optical response of materials and the functioning of opto-electronic devices. Yet, in all these decades, it has always been known that a fundamental degree of freedom of the exciton has been inaccessible – it’s momentum! Resolving the momentum coordinate of excitons could give direct access to rich excitonic phenomena – the excitonic wavefunction, hot excitons, confined excitons, dark excitons and how the presence of intense excitonic fields can drive electronic structure changes in the material!
In this talk, I will give a brief overview of the work in my labs at OIST to answer the above questions. We use time-resolved Momentum Microscopy to visualize dark excitons [1], image the electron around the hole inside the exciton [2], observe the long-predicted anomalous dispersion of the exciton-bound electron [2], resolve the momentum of the exciton-bound hole [3], access the confinement of the interlayer exciton in a moiré cell [3], observe exciton-driven electronic structure changes in materials [4] and further the possibility of dark valleytronics.
References
[1] J. Madeo, M. K. L. Man, et al. Science 370 2020
[2] M. K. L. Man, J. Madeo, et al. Science Advances 7 2021
[3] O. Karni, E. Barr, V. Pareek, J. D. Georgaras, M. K. L. Man C. Sahoo, et al. Nature 603 2022
[4] V. Pareek, D. Bacon, X. Zhu, et al, submitted.
[5] X. Zhu, D. Bacon, V. Pareek, et al submitted.
In this talk, I will give a brief overview of the work in my labs at OIST to answer the above questions. We use time-resolved Momentum Microscopy to visualize dark excitons [1], image the electron around the hole inside the exciton [2], observe the long-predicted anomalous dispersion of the exciton-bound electron [2], resolve the momentum of the exciton-bound hole [3], access the confinement of the interlayer exciton in a moiré cell [3], observe exciton-driven electronic structure changes in materials [4] and further the possibility of dark valleytronics.
References
[1] J. Madeo, M. K. L. Man, et al. Science 370 2020
[2] M. K. L. Man, J. Madeo, et al. Science Advances 7 2021
[3] O. Karni, E. Barr, V. Pareek, J. D. Georgaras, M. K. L. Man C. Sahoo, et al. Nature 603 2022
[4] V. Pareek, D. Bacon, X. Zhu, et al, submitted.
[5] X. Zhu, D. Bacon, V. Pareek, et al submitted.