Division of Laser Science Invited Symposium: New Development in Understanding and Controlling Excited States in Quantum MaterialsKeshav DaniExcitons in Momentum Space

Optical techniques have provided us with rich information about the exciton – a two-particle photoexcited state in semiconductors and insulators. Yet, they have left a fundamental degree of freedom of the exciton inaccessible – it’s momentum!

In this talk, I will discuss the application of time-resolved photoemission techniques to access the momentum coordinate of excitons in 2D semiconductors, thereby providing us with the formation pathways of momentum-forbidden dark excitons [1], an image of the electron around the hole in the exciton [2], the observation of the long-predicted anomalous dispersion of the exciton-bound electron [2], the momentum distribution of the exciton-bound hole [3], the confinement of the interlayer exciton in a moiré cell [3], the impact of excitons in the dense limit [4], and the dynamics of the spin-dark excitons [5].

References ( ^*equal authors)

[1] J. Madeo^*, M. K. L. Man^*, et al. Science 370, 1199 (2020).

[2] M. K. L. Man^*, J. Madeo^*, et al. Science Advances 7, eabg0192 (2021).

[3] O Karni^*, E. Barr^*, V. Pareek^*, J. D. Georgaras^*, M. K. L. Man^*, C. Sahoo^*, et al. Nature 603, 247 (2022).

[4] V. Pareek^*, D. Bacon^*, X. Zhu^*, et al. in prep

[5] D. Bacon^*, X. Zhu^*, V. Pareek^*, et al, in prep