Kitaev Meets Affleck-Kennedy-Lieb-Tasaki: Competing Quantum Disorder in Spin-3/2 Honeycomb Systems

TL;DR

This paper explores a spin-3/2 honeycomb model that interpolates between Kitaev quantum spin liquid and AKLT valence bond solid states, revealing how quantum fluctuations influence phase stability and entanglement.

Contribution

It introduces a comprehensive phase diagram for the model, demonstrating the fragility of classical orders and the emergence of quantum-entangled states due to quantum fluctuations.

Findings

Classical and semi-classical predictions of noncoplanar orders are destabilized by quantum fluctuations.

Quantum fluctuations lead to a quantum-entangled state with suppressed spin correlations.

Competition between different quantum disordered phases fosters unconventional quantum states.

Abstract

We investigate an S=3/2 quantum spin model on a two-dimensional honeycomb lattice that continuously interpolates between two paradigmatic quantum disordered states with distinct entanglement structures: the Kitaev quantum spin liquid and the Affleck-Kennedy-Lieb-Tasaki (AKLT) valence bond solid. Combining classical, semi-classical, and exact diagonalization approaches, we map out the ground-state phase diagram and elucidate the role of quantum fluctuations across the entire parameter range. While classical and semi-classical frameworks predict noncoplanar orders competing with a collinear N\'eel state, we find these phases to be fragile: once full quantum fluctuations are included, they melt into a quantum-entangled state characterized by suppressed spin correlations and enhanced entanglement entropy. Our findings highlight how competition between qualitatively different quantum disordered phases provides a fertile playground for unconventional phases emerging from their interplay and quantum fluctuations.