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

JuSER (Forschungszentrum Jülich)

Abstract

Artificial nanostructures, fabricated by placing building blocks such as atoms or molecules in well-defined positions, are a powerful platform in which quantum effects can be studied and exploited on the atomic scale. Here, we report a strategy to significantly reduce the electron-electron coupling between a large planar aromatic molecule and the underlying metallic substrate. To this end, we use the manipulation capabilities of a scanning tunneling microscope (STM) and lift the molecule into a metastable upright geometry on a pedestal of two metal atoms. Measurements at millikelvin temperatures and magnetic fields reveal that the bottom-up assembled standing metal-molecule nanostructure has an $S = \frac{1}{2}$ spin which is screened by the substrate electrons, resulting in a Kondo temperature of only $291 \pm 13$ mK. We extract the Landé $g$-factor of the molecule and the exchange coupling $Jρ$ to the substrate by modeling the differential conductance spectra using a third-order perturbation theory in the weak coupling and high-field regimes. Furthermore, we show that the interaction between the STM tip and the molecule can tune the exchange coupling to the substrate, which suggests that the bond between the standing metal-molecule nanostructure and the surface is mechanically soft.

Authors 4

1. Taner Esat corresponding

   Forschungszentrum Jülich · Jülich Aachen Research Alliance

   Affiliation as printed

   Jülich Aachen Research Alliance (JARA) , Fundamentals of Future Information Technology , 52425 Jülich , Germany

   Peter Grünberg Institute (PGI-3) , Forschungszentrum Jülich , 52425 Jülich , Germany

   Jülich Aachen Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany

   Peter Grünberg Institute (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany

2. Markus Ternes Aachen Institute of Physics II B

   Forschungszentrum Jülich · Jülich Aachen Research Alliance · RWTH Aachen University

   Affiliation as printed

   Institute of Physics II B, RWTH Aachen University, 52074 Aachen, Germany

   Jülich Aachen Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany

   Peter Grünberg Institute (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany

3. Ruslan Temirov

   Forschungszentrum Jülich · University of Cologne · Jülich Aachen Research Alliance

   Affiliation as printed

   Institute of Physics II, University of Cologne, 50937 Cologne, Germany

   Jülich Aachen Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany

   Peter Grünberg Institute (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany

4. Frank Stefan Tautz Aachen Experimental Physics IV A

   Forschungszentrum Jülich · Jülich Aachen Research Alliance · RWTH Aachen University

   Affiliation as printed

   Experimental Physics IV A, RWTH Aachen University, 52074 Aachen, Germany

   Jülich Aachen Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany

   Peter Grünberg Institute (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany