We successfully synthesized a verdazyl-based complex, (m-Py-V)3[Ni(NO3)2], in which Ni2+ ions and verdazyl radicals form a one-dimensional, triangular spin necklace consisting of spin-1/2 and spin-1 units. Molecular orbital calculations reveal strong antiferromagnetic (AF) interactions between inversion-related radical pairs that form spin-1/2 singlet dimers. The remaining verdazyl and Ni2+ spins form frustrated triangular units, creating a distinctive spin network. Magnetic susceptibility and specific heat measurements identify a phase transition to an AF order. The application of magnetic fields suppresses the phase transition signal, suggesting field-induced decoupling of the spin-1 moments. Electron spin resonance measurements are used to evaluate the easy-axis anisotropy of spin-1, which may promote the AF order. This work provides a rare example of a geometrically frustrated quantum spin chain realized via molecular design, thereby offering a platform for exploring frustration-driven quantum phases in low-dimensional materials.
Cite
@article{arxiv.2601.16389,
title = {Realization of a triangular spin necklace in a verdazyl-based Ni complex},
author = {Itsuki Shimamura and Risa Yagura and Takanori Kida and Masayuki Hagiwara and Koji Araki and Yoshiki Iwasaki and Yuko Hosokoshi and Kenta Kimura and Hironori Yamaguchi},
journal= {arXiv preprint arXiv:2601.16389},
year = {2026}
}