NCAFM2023 Programme Booklet

Wednesday 1520-1540

Jung-Ching Liu1*, Chao Li1, Outhmane Chahib 1 , Xing Wang 2 , Ping Zhou 2 , Robert Häner 2 , Silvio Decurtins 2 , Ulrich Aschauer 2 , Shi-Xia Liu 2 , Ernst Meyer 1* , Rémy Pawlak 1 1 Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland 2 Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland Email: jungching.liu@unibas.ch, ernst.meyer@unibas.ch SPIN-FLIP EXCITATIONS IN ORGANOMETALLIC CHAINS

Controlling the spin of metal adatoms in well-ordered metal-organic frameworks is a key step towards the realization of molecular electronics and spintronics. However, the survival or quenching of magnetic moments in such structures is dictated by the interaction between the adatom and the surrounding molecules as well as with the underlying substrate [1]. An understanding of the magnetic ground state of these metal centers into complex assemblies is thus primordial at the atomic scale. Here, we show the synthesis of long metal-organic chains on Ag(111) and Pb(111) by co-assembling pyrene-4,5,9,10-tetraone (PTO) molecules and Fe adatoms [2]. Scanning tunneling microscopy (STM) and atomic force microscopy (AFM) with CO-terminated tips [3] reveals the structure of the adsorbed organometallic chains. Tunneling spectroscopy at 1 K indicates three spin-flip excitations at the Fe atoms, which are assigned to spin-flip events. On Pb(111), PTO-Fe organometallic chains show two spin-flip excitations outside the superconducting gap. By comparing these two systems, we conclude that the spin characteristics of the PTO-Fe chain do not change drastically between these substrates, yet spin state excitation is expected to have a longer lifetime on a superconductor [4,5]. We believe our study our work provides a route for fundamental studies in spin-spin and spin-substrate interactions with different lattice structures.

Fig. 1: a The STM image of the PTO assembly on Ag(111) with the substrate kept at room temperature. b , The AFM image of the PTO assembly shows a rotational angle between adjacent rows. c , The DFT calculation agrees with the experimental observation. d , The STM image of PTO-Fe chains on Ag(111). e , The AFM image confirms the successful synthesis of PTO-Fe chains. f , The DFT simulation shows Fe atoms on the hollow sites of Ag(111).

References [1] Heinrich et al., Science, 2004, 306 , 466-469. [2] Pia et al. Chem. Eur. J., 2016, 22 , 8105-8112. [3] Gross et al., PRL, 2011, 107, 086101. [4] Heinrich et al. Nat. Phys., 2013, 9 , 765-768. [5] Vaxevani et al., Nano Lett. 2022, 22 , 6075-6082.

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