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O: Fachverband Oberflächenphysik
O 59: Spins on Surfaces at the Atomic Scale I
O 59.4: Vortrag
Mittwoch, 19. März 2025, 11:15–11:30, H6
Nickelocene-functionalized tips as a molecular spin sensor — •Diego Soler-Polo1, Ana Barragán2, Andrés Pinar Solé1, Manish Kumar1, Oleksandr Stetsovych1, Ben Lowe1, Elena Pérez-Elvira2, Koen Lauwaet2, Pavel Jelínek2, and José Ignacio Urgel2 — 1Institute of Physics of the Czech Academy of Sciences, Prague, Czech Republic — 2IMDEA Nanoscience, Cantoblanco, Madrid, Spain
Polyradicals nanographenes with low-lying spin excitations have almost degenerate states with different spins. Even Many-Body methods such as CASSCF and NEVPT2 might not provide enough accuracy to determine the spin of the real ground state. Here, we demonstrate that scanning probe microscopy with a nickelocene-functionalized tip can distinguish between nearly degenerate spin states of single molecular π-magnets. The nickelocene molecule has a spin 1 and a small magnetic anisotropy of 4 meV that interacts with the molecular spins of the sample. The spectroscopic patterns as we the tip is approached can be related to the number of radicals and their couplings. Such patterns are well reproduced by simple spin models and the corresponding simulated inelastic current. First, the molecular radicals are fitted to a spin hamiltonian, which is then coupled to the S=1 modelling the nickelocene. A cotunneling formalism adapted to spin hamiltonians provides the dIdV maps comparable with the experimental measurements, thus revealing the spin of the sampled system.
Keywords: Nickelocene tip; Nanographenes; Many-body physics; STM; Spin models