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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 30: 2D Materials II: Electronic Structure, Excitations, etc. (joint session O/CPP/HL)

CPP 30.5: Vortrag

Montag, 16. März 2020, 16:00–16:15, WIL C107

Final-State Effects in Photoemission from Black Phosphorus — •Charlotte E. Sanders¹, Irene Aguilera², Klara Volkaert³, Deepnarayan Biswas³, Marco Bianchi³, and Philip Hofmann³ — ¹Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell OX11 0QX, UK — ²Institute of Energy Research - Photovoltaic, Forschungszentrum Jülich, D-52425 Jülich, Germany — ³Department of Physics and Astronomy, Aarhus University, 8000-C Aarhus, Denmark

Intrinsically doped bulk black phosphorus, although a van der Waals layered crystal, has nontrivial interlayer interactions and out-of-plane dispersing (k_z) electronic states, with a direct bandgap at the Z point of the three-dimensional (3D) Brillouin zone. The material’s 3D character is related to key properties such as the thickness dependence of the bandgap in thin films and the tunability of the bandgap by strain and electric field. Interestingly, studies from angle-resolved photoemission spectroscopy (ARPES) of the k_z dispersion reveal intensity modulations near the Fermi level that are difficult to interpret in terms of the valence band dispersion predicted by theory. They have been attributed to surface-resonant states [1,2]. However, on the basis of density functional theory calculations and ARPES data acquired across a broad photon energy range, we suggest here an alternative interpretation based on final-state effects. The results call attention to the meaning of the free-electron-like final-state assumption and to the limits of its applicability. [1] PRB 90 (2014) 085101. [2] PRB 93 (2016) 075207.