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

TL;DR

This study demonstrates how a rare-earth surface alloy influences the magnetic properties of nanographenes, revealing a proximity-induced magnetic interaction that can be spatially modulated, advancing the integration of magnetic nanomaterials.

Contribution

It provides the first experimental and theoretical evidence of magnetic proximity effects on nanographenes using a rare-earth alloy substrate, revealing spatially modulated magnetic interactions.

Findings

Deposition on TbAu2 splits the Kondo resonance in nanographenes.

The magnetic interaction is spatially modulated by the surface superstructure.

TbAu2 can stabilize and probe the magnetic properties of nanographenes.

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.