Submitted (2025)
Chengyi Chen#, Hua Zhu#, En Li, Henan Chen, Huilin Xie, Jacky W. Y. Lam, Ben Zhong Tang, Wei Ji*, and Nian Lin*
Abstract:
The low spin–orbit coupling and weak hyperfine interactions make organic radicals promising components used in molecular spintronics. Triphenylmethyl is the first stable carbon-centered organic radicals discovered more than a century ago. Here we use scanning tunneling spectroscopy to study quantum transport through single triphenylmethyl radicals that are attached to a Au(111) electrode via atomic contacts of Ni atoms. The transport exhibits a Kondo resonance evidencing the unpair electron of the radical forms a spin singlet with the itinerary electrons of the electrode. Density functional theory calculations reveal an indirect Kondo screening mechanism: the itinerary electrons couple with the radical π electron via the d orbitals of the Ni atoms. These results envision a new way to regulate spin transport of organic radicals using atomic contacts in solid state spintronic devices.
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