Spatially Resolving Electron Spin Resonance of π-Radical in Single-molecule Magnet.

Kawaguchi, Ryo; Hashimoto, Katsushi; Kakudate, Toshiyuki; Katoh, Keiichi; Yamashita, Masahiro; Komeda, Tadahiro · Nano Lett · 2023

basic_science · Level V

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Abstract

The spintronic properties of magnetic molecules have attracted significant scientific attention. Special emphasis has been placed on the qubit for quantum information processing. The single-molecule magnet bis(phthalocyaninato (Pc)) Tb(III) (TbPc<sub>2</sub>) is one of the best examined cases in which the delocalized π-radical electron spin of the Pc ligand plays the key role in reading and intermediating the localized Tb spin qubits. We utilized the electron spin resonance (ESR) technique implemented on a scanning tunneling microscope (STM) and use it to measure local the ESR of a single TbPc<sub>2</sub> molecule decoupled from the Cu(100) substrate by a two-monolayer NaCl film to identify the π-radical spin. We detected the ESR signal at the ligand positions under the resonance condition expected for an <i>S</i> = 1/2 spin. The results reveal that the π-radical electron is delocalized within the ligands and exhibits intramolecular coupling susceptible to the chemical environment.