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

Ryo Kawaguchi; Katsushi Hashimoto; Toshiyuki Kakudate; Keiichi Katoh; Masahiro Yamashita; Tadahiro Komeda

doi:10.1021/acs.nanolett.2c04049

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

Nano Lett. 2023 Jan 11;23(1):213-219. doi: 10.1021/acs.nanolett.2c04049. Epub 2022 Dec 31.

Authors

Ryo Kawaguchi¹, Katsushi Hashimoto^{2

3}, Toshiyuki Kakudate⁴, Keiichi Katoh⁵, Masahiro Yamashita^{6

7}, Tadahiro Komeda^{1

3}

Affiliations

¹ Institute of Multidisciplinary Research for Advanced Materials (IMRAM, Tagen), Tohoku University, Sendai980-0877, Japan.
² Department of Physics, Graduate School of Sciences, Tohoku University, Sendai980-8578, Japan.
³ Center for Science and Innovation in Spintronics (Core Research Cluster), Tohoku University, Sendai980-8577, Japan.
⁴ Department of Industrial Systems Engineering, National Institute of Technology (KOSEN), Hachinohe College, 16-1 Uwanotai, Tamonoki, Hachinohe039-1192, Japan.
⁵ Department of Chemistry, Graduate School of Science, Josai University, Sakado, Saitama350-0295, Japan.
⁶ Department of Chemistry, Graduate School of Science, Tohoku University, Sendai980-8578, Japan.
⁷ School of Materials Science and Engineering, Nankai University, Tianjin300350, People's Republic of China.

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) (TbPc₂) 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 TbPc₂ 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 S = 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.

Keywords: Double-Decker Phthalocyaninato Terbium (TbPc2); Electron Spin Resonance; Scanning Tunneling Microscopy; Single-Molecule Magnet (SMM); π-Radical.