Li2RuO3 with a honeycomb structure undergoes a drastic transition from a regular honeycomb lattice with the C2/m space group to a valence bond solid state of the P21/m space group with an extremely strong dimerization at 550 K. We synthesized Li2Ru1−xMnxO3 with a full solid solution and investigated doping effects on the valence bond solid state as a function of Mn content. The valence bond solid state is found to be stable up to x=0.2, based on our extensive experiments: structural studies, resistivity, and magnetic susceptibility. On the other hand, the extended x-ray absorption fine structure analyses show that the dimer local structure remains robust even above x=0.2 with a minimal effect on the dimer bond length. This indicates that the locally-disordered dimer structure survives well into the Mn-rich phase even though the thermodynamically stable average structure has the C2/m space group. Our results prove that the dimer formation in Li2RuO3 is predominantly a local phenomenon driven by the formation of orbitally-assisted metal-metal bonds and that these dimers are relatively robust against doping-induced disorder.
@article{arxiv.2010.16028,
title = {Doping effects on the valence bond solid of Li$_{2}$RuO$_{3}$ with Mn substitution},
author = {Seokhwan Yun and Ki Hoon Lee and Chaebin Kim and Junghwan Park and Min-Gyu Kim and Deok-Yong Cho and D. I. Khomskii and Je-Geun Park},
journal= {arXiv preprint arXiv:2010.16028},
year = {2021}
}