Regensburg 2025 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 11: Electronic Structure of Surfaces: Spectroscopy, Surface States I

O 11.4: Vortrag

Montag, 17. März 2025, 15:45–16:00, H4

Surface Orbitroscopy: Emergent Phenomena of Orbital Angular Momentum — •Maximilian Ünzelmann¹, Tim Figgemeier¹, Begmuhammet Geldiyev¹, Hendrik Bentmann², and Friedrich Reinert¹ — ¹Exp. Physik VII and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, Germany — ²QuSpin, NTNU Trondheim, Norway

Quantum degrees of freedom in electronic states are a key facet of modern quantum materials. Recently, the orbital angular momentum (OAM) — an orbital analogue of electron spin — has attracted broad attention in condensed matter and surface physics. For instance, orbitronics has been predicted as a promising route towards new functionalities, such as low-dissipation orbital currents or magnetization switching by orbital torques. In this talk, I will present orbital-sensitive angle-resolved photoemission spectroscopy experiments that demonstrate three key features of the OAM: (i) it acts as a central mediator between lattice and spin in spin-orbit-coupled systems, such as Rashba-type surface states [1,2], (ii) it might be associated with orbital currents, and (iii) its momentum texture carries topological information, giving rise to intriguing paradigms like OAM monopoles [3] or momentum-space quantum vortices [4].
[1] M. Ünzelmann et al., Phys. Rev. Lett. 124, 176401 (2021), [2] B. Geldiyev, M.Ü., et al., Phys. Rev. B 108, L121107 (2023), [3] M. Ünzelmann et al., Nat. Commun. 12, 3650 (2021), [4] T. Figgemeier, M.Ü., et al., arXiv:2402.10031 (2024)

Keywords: Electronic Structure; ARPES; Orbital Angular Momentum; Orbitronics