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

TL;DR

This paper investigates how weakened trimer frustration in LiVO2 affects its stacking order and transition temperature, revealing that reduced frustration leads to higher transition temperatures and the presence of short-range order.

Contribution

The study introduces a novel modeling scheme to represent disordered trimer configurations and demonstrates how synthesis methods influence stacking order and phase transition temperatures.

Findings

Disordered stacking structure lowers transition temperature by about 15 K.

Two types of stacking structures identified: disordered and short-range ordered.

Weakened trimer frustration correlates with increased transition temperature.

Abstract

Vanadium atoms in layered LiVO2 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 PDF 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.