Robust singlet dimers with fragile ordering in two-dimensional honeycomb lattice of Li$_2$RuO$_3$

TL;DR

This study investigates how doping affects the fragile valence bond crystal phase in Li₂RuO₃, revealing a transition to a resonating valence bond liquid, thus providing insights into quantum phase competition in correlated systems.

Contribution

It demonstrates the doping-induced melting of a valence bond crystal into a resonating valence bond liquid in Li₂RuO₃, advancing understanding of quantum phase transitions in correlated materials.

Findings

VBC phase melts into RVB liquid with doping

Doping dependence reveals fragile quantum entangled states

Experimental evidence of phase transition in Li₂RuO₃

Abstract

When an electronic system has strong correlations and a large spin-orbit interaction, it often exhibits a plethora of mutually competing quantum phases. How a particular quantum ground state is selected out of several possibilities is a very interesting question. However, equally fascinating is how such a quantum entangled state breaks up due to perturbation. This important question has relevance in very diverse fields of science from strongly correlated electron physics to quantum information. Here we report that a quantum entangled dimerized state or valence bond crystal (VBC) phase of Li2RuO3 shows nontrivial doping dependence as we perturb the Ru honeycomb lattice by replacing Ru with Li. Through extensive experimental studies, we demonstrate that the VBC phase melts into a valence bond liquid phase of the RVB (resonating valence bond) type. This system offers an interesting playground where one can test and refine our current understanding of the quantum competing phases in a single compound.