Signatures of magnetic-field-driven quantum phase transitions in the entanglement entropy and spin dynamics of the Kitaev honeycomb model

TL;DR

This paper investigates how magnetic fields influence quantum phase transitions in the Kitaev honeycomb model, revealing a gapless quantum spin liquid phase and its signatures in entanglement and spin dynamics.

Contribution

It identifies a field-induced gapless QSL phase and characterizes its signatures in entanglement entropy and spin dynamics, providing insights into experimental detection.

Findings

Discovery of a gapless QSL phase between non-Abelian and polarized phases.

Reduction of frequency modes and emergence of beating patterns near polarized limit.

Potential observability of dynamical correlation patterns in pump-probe experiments.

Abstract

The main question we address is how to probe the fractionalized excitations of a quantum spin liquid (QSL), for example, in the Kitaev honeycomb model. By analyzing the energy spectrum and entanglement entropy, for antiferromagnetic couplings and a field along either [111] or [001], we find a gapless QSL phase sandwiched between the non-Abelian Kitaev QSL and polarized phases. Increasing the field strength towards the polarized limit destroys this intermediate QSL phase, resulting in a considerable reduction in the number of frequency modes and the emergence of a beating pattern in the local dynamical correlations, possibly observable in pump-probe experiments.