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Electron spin secluded inside a bottom-up assembled standing metal-molecule nanostructure

Taner Esat

Artificial nanostructures, fabricated by placing atoms or molecules as building blocks in well-defined positions, are a powerful platform in which quantum effects can be studied and exploited. In this talk, I will report a strategy to strongly reduce the electronic coupling between a large aromatic molecule and the underlying metallic substrate. To this end, we use the manipulation capabilities of scanning tunneling microscopy and lift the molecule into an upright geometry on a pedestal of two metal atoms [1]. Measurements at millikelvin temperatures and in magnetic fields in a novel homebuilt STM based on adiabatic demagnetization refrigeration (ADR) [2] reveal that this bottom-up assembled standing metal-molecule nanostructure has an S = 1/2 spin which is screened by substrate electrons, resulting in a Kondo temperature of only 291±13 mK [3]. We extract the Landé g factor and the exchange coupling Jρ to the substrate, using a third-order perturbation theory in the weak-coupling and high-field regimes. We also show that the interaction between the STM tip and the molecule can tune the exchange coupling.


[1] T. Esat, N. Friedrich, F.S. Tautz, R. Temirov. A standing molecule as a single-electron field emitter. Nature 558, 573-576 (2018).

[2] T. Esat, P. Borgens, X. Yang, P. Coenen, V. Cherepanov, A. Raccanelli, F.S. Tautz, R. Temirov. A millikelvin scanning tunneling microscope in ultra-high vacuum with adiabatic demagnetization refrigeration. Review of Scientific Instruments 92, 063701 (2021).

[3] T. Esat, M. Ternes, R. Temirov, F.S. Tautz. Electron spin secluded inside a bottom-up assembled standing metal-molecule nanostructure. arXiv preprint arXiv:2301.11762 (2023).