Short-range order and increased transition temperature in LiVO2 with weakened trimer frustration

Vanadium atoms in layered $\mathrm{Li}\mathrm{V}{\mathrm{O}}₂$ form in-plane periodic vanadium trimers at low temperatures, but the trimers appear randomly in the stacking direction because there are many trimer configurations with comparable lattice energy. We detailed an original modeling scheme to represent glassy states with a completely disordered trimer configuration in the stacking structure. Through pair distribution function analysis using this model, we show that the synthesis method can yield two types of low-temperature stacking structures: a completely disordered stacking structure and a short-range order in the stacking structure. The phase-transition temperature of the former sample is about 15 K lower than that of the latter. We discuss that this is due to the strong trimer frustration that appears in the sample without short-range order, which suppresses the phase-transition temperature, similar to the frustration effect in conventional spin systems.