Regensburg 2025 – scientific programme
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O: Fachverband Oberflächenphysik
O 90: Spins on Surfaces at the Atomic Scale II
O 90.2: Talk
Thursday, March 20, 2025, 15:15–15:30, H11
Electric Control of Molecular Spins on a Surface — •Paul Greule1, Wantong Huang1, Máté Stark1, Kwan Ho Au-Yeung1, Christoph Sürgers1, Wolfgang Wernsdorfer1, Christoph Wolf2, and Philip Willke1 — 1Physikalisches Institut (PHI), Karlsruhe Institute of Technology, Karlsruhe, Germany — 2Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
Single electronic spins hosted by atoms or molecules are candidates for future quantum technologies. To utilize them as functional building blocks in quantum information processing it is necessary to gain local control of their quantum properties. Lately, electron spin resonance combined with scanning tunnelling microscopy (ESR-STM) was demonstrated as a versatile method to access atoms and molecules on a surface [1]. For single Ti atoms it was shown that the Zeeman energy of electron spins can be tuned via the applied bias voltage in the tunnelling junction [2] constituting an atomic-scale electric field control. In our work, we present a voltage-dependent shift of the ESR frequency for two different molecular spin systems, Iron-phthalocyanine (FePc) and FePc-Fe ferrimagnet complexes. Intriguingly, we observe a strong non-linearity in the shift connected to the molecular orbital of FePc. We rationalize this theoretically by many-body interactions with the exchange bias field of the tip. Moreover, we show how the bias voltage control can be used to detune Rabi oscillations in pulsed ESR experiments. [1] Y. Chen et al., Adv. Mater. 2022, 2107534 [2] P. Kot et al., Nat Commun 14, 6612 (2023)
Keywords: electric control; quantum manipulation; molecular spins; electron spin resonance