Honeycomb oxide heterostructure: a new platform for Kitaev quantum spin liquid

TL;DR

This paper reports the synthesis and characterization of a honeycomb oxide thin film, Na3Co2SbO6, as a candidate for realizing Kitaev quantum spin liquid, demonstrating quantum criticality and strong frustration.

Contribution

It introduces epitaxial honeycomb oxide thin films as a new platform for exploring Kitaev quantum spin liquids, highlighting the role of stoichiometry and quantum critical behavior.

Findings

Na3Co2SbO6 exhibits spin glass and antiferromagnetic states depending on Na content.

Magnetic susceptibility shows quantum critical scaling behavior.

Electronic structure aligns with the Kitaev model predictions.

Abstract

Kitaev quantum spin liquid, massively quantum entangled states, is so scarce in nature that searching for new candidate systems remains a great challenge. Honeycomb heterostructure could be a promising route to realize and utilize such an exotic quantum phase by providing additional controllability of Hamiltonian and device compatibility, respectively. Here, we provide epitaxial honeycomb oxide thin film Na3Co2SbO6, a candidate of Kitaev quantum spin liquid proposed recently. We found a spin glass and antiferromagnetic ground states depending on Na stoichiometry, signifying not only the importance of Na vacancy control but also strong frustration in Na3Co2SbO6. Despite its classical ground state, the field-dependent magnetic susceptibility shows remarkable scaling collapse with a single critical exponent, which can be interpreted as evidence of quantum criticality. Its electronic ground state and derived spin Hamiltonian from spectroscopies are consistent with the predicted Kitaev model. Our work provides a unique route to the realization and utilization of Kitaev quantum spin liquid.