Dresden 2026 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 9: 2D Materials: Electronic structure, excitations, etc. I (joint session O/HL/TT)
TT 9.4: Talk
Monday, March 9, 2026, 11:30–11:45, TRE/MATH
Surface-state engineering for nonlinear charge and spin photocurrent generation — •Javier Sivianes1, Peio Garcia-Goiricelaya2, Daniel Hernangómez-Pérez3, and Julen Ibañez-Azpiroz1,4,5 — 1Centro de Física de Materiales (CSIC-UPV/EHU), Donostia, Spain — 2University of the Basque Country UPV/EHU, Leioa, Spain — 3CIC nanoGUNE BRTA, San Sebastián, Spain — 4IKERBASQUE, Basque Foundation for Science, Bilbao, Spain — 5Donostia International Physics Center (DIPC), Donostia, Spain
We systematically explore the generation of nonlinear charge and spin photocurrents using spin-orbit-split surface states. This mechanism enables net DC flow along the surface plane even in centrosymmetric bulk environments like the Rashba prototype Au(111), where we characterize the main quadratic contributions by combining model predictions with density functional calculations. We further identify the Tl/Si(111) surface as a prime scenario for experimental verification; with slight doping, it develops metallic surface states featuring remarkable relativistic properties deviating from the Rashba paradigm, while the bulk remains semiconducting. Its nonlinear charge photocurrent reveals a distinct angular signature and a magnitude comparable to bulk ferroelectrics, highlighting the potential of surface-state photocurrents for low-bias optoelectronic applications. Moreover, the non-trivial spin texture of its surface states enables the generation of pure out-of-plane spin-polarized currents, offering a highly versatile nonlinear spin-filtering functionality beyond the conventional spin Hall effect.
Keywords: Surface states; Non-linear optics; Non-linear spin currents; Spin-split states