Dresden 2026 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 96: Plasmonics and nanooptics: Fabrication, characterization and applications
O 96.5: Vortrag
Freitag, 13. März 2026, 10:30–10:45, HSZ/0403
Nanoscale Optical Readout of Antiferromagnetic Order by Photocurrent Nanoscopy — •Dario Siebenkotten1, Anna Schmid2, Dinghe Dai1, Joao Godinho2, Sam Fairman1, Arne Hoehl1, Tomas Janda2, Tomas Ostatnicky3, Bernd Kästner1, and Jörg Wunderlich2 — 1Physikalisch-Technische Bundesanstalt, Berlin, Germany — 2Institute of Experimental and Applied Physics, University of Regensburg, Regensburg, Germany — 3Charles University, Faculty of Mathematics and Physics, Prague, Czech Republic
Antiferromagnets are prime candidates for next-generation spintronic technologies as they allow for rapid switching and miniaturization compared to ferromagnets. However, readout of their magnetic state remains an open challenge, as their vanishing net magnetisation suppresses conventional magnetic readout schemes. Therefore, new mechanisms are required to measure the state of antiferromagnetic domains, which are often confined to the nanoscale. Here, we report on the experimental observation of a previously only theoretically predicted light-induced, Néel-order-dependent transverse photocurrent that we refer to as the optical nonlinear anomalous Hall effect. We demonstrate the effect by nanoscale imaging of the photocurrent generated in PT-symmetric CuMnAs cross-bar devices by mid-infrared near fields at the apex of a sharp metal tip. We exclude purely thermal mechanisms by showing that the photocurrent reverses sign when the Néel vector is rotated by 180° via current-induced switching of nanoscale antiferromagnetic domains of a few hundred nanometers in size, consistent with a time-reversal-odd nonlinear anomalous Hall photocurrent.
Keywords: Photocurrent Nanoscopy; Anomalous Hall Effect; Collinear Antiferromagnets; Infrared Near-Field Microscopy