Regensburg 2025 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 68: Focus Session Molecular Nanostructures on Surfaces: On-Surface Synthesis and Single-Molecule Manipulation IV
O 68.10: Vortrag
Mittwoch, 19. März 2025, 17:30–17:45, H24
An electrically controlled molecular spin switch — •Kwan Ho Au-Yeung1, Wantong Huang1, Paul Greule1, Máté Stark1, Christoph Sürgers1, Wolfgang Wernsdorfer1, Roberto Robles2, Nicolas Lorente2,3, and Philip Willke1 — 1Physikalisches Institut, Karlsruhe Institute of Technology, Karlsruhe, Germany — 2Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), 20018 Donostia-San Sebastián, Spain — 3Donostia International Physics Center, 20018 Donostia-San Sebastián, Spain
Precise control of spin states and spin-spin interactions in atomic-scale molecular complexes is key to developing multi-spin systems on surfaces for instance for applications in quantum technologies. This has been realized in a variety of systems, for instance in spin-crossover molecules. In this study, we explore the spin coupling and tunability of molecular dimer complexes on an insulating magnesium oxide film: When brought close to a single Fe adatom, a FePc molecule interacts with the Fe forming an interacting spin system. The calculated adsorption geometries by density functional theory (DFT) shed light on the two adsorption configurations of the two bistable states. The two states of the Fe-FePc complex can be successfully and reversibly switched using STM voltage pulses. Subsequently, by using scanning tunneling spectroscopy, we show that this is accompanied by an alteration of the total spin state and spin coupling in the complex. We further illustrate how the complex can be used to shift the resonance frequency of a nearby FePc in single spin resonance experiments, which demonstrates that this complex can function as a magnetic spin switch.
Keywords: Molecular machine; Single molecule magnet; Electron spin resonance; Inelastic tunneling spectroscopy; Density functional theory