Regensburg 2025 – scientific programme
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O: Fachverband Oberflächenphysik
O 16: Scanning Probe Techniques: Method Development
O 16.7: Talk
Monday, March 17, 2025, 16:30–16:45, H25
Momentum-polarized microscopy with van der Waals scanning probe tip. — •Abhisek Kole1,2,4, Frank Stefan Tautz1,2,4, Markus Ternes1,2,3, Jose Martinez Castro1,2,3, and Felix Lüpke1,2,5 — 1Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, Germany — 2Jülich Aachen Research Alliance, Fundamentals of Future Information Technology, Germany — 3Institut fur Experimentalphysik II B, RWTH Aachen, Aachen, Germany — 4Institut fur Experimentalphysik IV A, RWTH Aachen, Aachen, Germany — 5II. Physikalisches Institut, Universität zu Köln, Cologne, Germany
Van der Waals materials are celebrated for their remarkable 2D physics, which includes correlated phenomena and topological effects. In this work, we present momentum-polarized microscopy using a van der Waals scanning probe tip. We developed and implemented a novel fabrication method to fabricate van der Waals scanning tunneling tips from exfoliated graphite flakes. The fabricated tips were characterized by atomically resolved scanning tunneling microscopy (STM) on an Ag(111) surface, where differential conductance measurements provided direct evidence of tunneling through the zigzag edge states of graphene. In addition, Friedel oscillations on the Ag(111) surface revealed clear signs of momentum-dependent tunneling, manifesting as anisotropic tunneling conductance. To further validate and investigate the momentum selective properties of the zigzag graphene tips, we have resolved the momentum dependent superconducting gap on FeSe lattices.
Keywords: Momentum-polarized tunnelling microscopy; Scanning tunnelling microscopy; Van der waals materials; Graphene; Superconductivity