Sensing a magnetic rare-earth surface alloy by proximity effect with an open-shell nanographene

Nicolò Bassi; Jan Wilhelm; Nils Krane; Feifei Xiang; Patrícia Čmelová; Elia Turco; Pierluigi Gargiani; Carlo Pignedoli; Michal Juríček; Roman Fasel; Richard Koryt ár; Pascal Ruffieux; .

arXiv · 2505.10313

Sensing a magnetic rare-earth surface alloy by proximity effect with an open-shell nanographene

Nicolò Bassi·Jan Wilhelm·Nils Krane·Feifei Xiang·Patrícia Čmelová·Elia Turco·Pierluigi Gargiani·Carlo Pignedoli·Michal Juríček·Roman Fasel·Richard Koryt ár·Pascal Ruffieux·.

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Abstract

Open-shell nanographenes have attracted significant attention due to their structurally tunable spin ground state. While most characterization has been conducted on weakly-interacting substrates such as noble metals, the influence of magnetic surfaces remains largely unexplored. In this study, we investigate how TbAu2, a rare-earth-element-based surface alloy, affects the magnetic properties of phenalenyl (or [2]triangulene (2T)), the smallest spin-1/2 nanographene. Scanning tunneling spectroscopy (STS) measurements reveal a striking contrast: while 2T on Au(111) exhibits a zero-bias Kondo resonance - a hallmark of a spin-1/2 impurity screened by the conduction electrons of the underlying metal - deposition on TbAu2 induces a symmetric splitting of this feature by approximately 20 mV. We attribute this splitting to a strong proximity-induced interaction with the ferromagnetic out-of-plane magnetization of TbAu2. Moreover, our combined experimental and first-principles analysis demonstrates that this interaction is spatially modulated, following the periodicity of the TbAu2 surface superstructure. These findings highlight that TbAu2 serves as a viable platform for stabilizing and probing the magnetic properties of spin-1/2 nanographenes, opening new avenues for the integration of {\pi}-magnetic materials with magnetic substrates.

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Nicolò Bassi, Jan Wilhelm, Nils Krane, Feifei Xiang, Patrícia Čmelová, Elia Turco, Pierluigi Gargiani, Carlo Pignedoli, Michal Juríček, Roman Fasel, Richard Koryt ár, Pascal Ruffieux, .. 2025-05-15. Sensing a magnetic rare-earth surface alloy by proximity effect with an open-shell nanographene. https://arxiv.org/abs/2505.10313

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