Non-equilibrium Electrons Dynamics as Observed in Time-Resolved Photoemission
Yaroslav Pavlyukh (Martin-Luther-Universität Halle-Wittenberg)

Photoemission is a well established phenomenon and an instrument for physical studies with more than a hundred years history (photoelectric effect). Thanks to recent advances in ultrafast lasers and streaking techniques it became possible [1, 2] to trace the electron dynamics accompanying this process on the attosecond time-scale. In my talk I will address from theoretical point of view the following facets of such dynamics: i) time delay of electrons experiencing extrinsic and intrinsic energy losses [3] as observed in recent experiment on bulk Mg [4]; ii) transient build up of plasmonic excitations in C60 and emission of the secondary electron [5,6]; iii) long-lived quantum beatings resolved in time by two-photon photoemission from antiferromagnetic NiO [7]. I will also briefly present a methodological aspect of such studies, namely propagation of the coupled electron-boson Kadanoff-Baym equations describing the non-equilibrium electrons dynamics.

References:

[1] R. Huber et al. How many-particle interactions develop after ultrafast excitation of an electron–hole plasma, Nature 414, 6861 (2001)

[2] R. Pazourek, S. Nagele, and J. Burgdörfer, Attosecond chronoscopy of photoemission, Rev. Mod. Phys. 87, 765 (2015)

[3] M. Schüler, J. Berakdar and Y. Pavlyukh, Time-dependent many-body treatment of electron-boson dynamics: Application to plasmon-accompanied photoemission, Phys. Rev. B 93, 054303 (2016)

[4] C. Lemell et al. Real-time observation of collective excitations in photoemission, Phys. Rev. B 91, 241101(R) (2015)

[5] M. Schüler,Y. Pavlyukh, P. Bolognesi, L. Avaldi, and J. Berakdar, Electron pair escape from fullerene cage via collective modes, Scientific Reports 6, 24396 (2016)

[6] Y. Pavlyukh, M. Schüler and J. Berakdar, Single- or double-electron emission within the Keldysh nonequilibrium Green's function and Feshbach projection operator techniques, Phys. Rev. B. 91, 155116 (2015)

[7] K. Satitkovitchai, Y. Pavlyukh, and W. Hübner, Ab initio study of spin-orbit coupling effects on the low-lying excited states of NiO, Phys. Rev. B. 72, 045116 (2005)