Field-induced Kitaev multipolar liquid in spin-orbit coupled $d^{2}$ honeycomb Mott insulators

TL;DR

This paper proposes a new quantum spin liquid phase called the Kitaev multipolar liquid in $d^{2}$ honeycomb Mott insulators, driven by magnetic field-induced multipole interactions, expanding the understanding of bond-dependent interactions beyond dipoles.

Contribution

It introduces a microscopic mechanism for realizing a Kitaev multipolar liquid involving quadrupole and octupole moments in $5d^2$ Mott insulators under magnetic fields.

Findings

Identification of conditions for realizing the phase in materials

Proposal of magnetic field as a key control parameter

Description of fractionalized excitations in the phase

Abstract

The Kitaev model, characterized by bond-dependent Ising spin interactions among spin-orbit entangled dipole moments in Mott insulators, offered a new approach to quantum spin liquids. Motivated by another type of bond-dependent interaction among quadrupole moments in $5d^2$ Mott insulators, we provide a microscopic route to uncover the Kitaev multipolar liquid, featuring fractionalized excitations out of non-Kramers doublets carrying multipole moments. The key ingredient is the magnetic field that allows for bond-anisotropic quadrupole-octupole interactions via mixing with the excited triplet states. The conditions to realize signatures of this phase in real materials are also discussed.