13C nuclear magnetic resonance measurements were performed for a single-component molecular material Zn(tmdt)2, in which tmdt's form an arrangement similar to the so-called κ-type molecular packing in quasi-two-dimensional Mott insulators and superconductors. Detailed analysis of the powder spectra uncovered local spin susceptibility in the tmdt π orbitals. The obtained shift and relaxation rate revealed the singlet-triplet excitations of the π spins, indicating that Zn(tmdt)2 is a spin-gapped Mott insulator with exceptionally large electron correlations compared to conventional molecular Mott systems.
@article{arxiv.1706.02030,
title = {A spin-gapped Mott insulator with the dimeric arrangement of twisted molecules Zn(tmdt)$_{2}$},
author = {Rina Takagi and Hiro Gangi and Kazuya Miyagawa and Biao Zhou and Akiko Kobayashi and Kazushi Kanoda},
journal= {arXiv preprint arXiv:1706.02030},
year = {2017}
}