Microscopic Mechanism for a Higher-Spin Kitaev Model.

Area of Science:

• Condensed Matter Physics
• Quantum Materials
• Solid-State Chemistry

Background:

• The spin S=1/2 Kitaev honeycomb model is crucial for studying non-Abelian anyons.
• Higher spin Kitaev models offer alternative routes to quantum spin liquids but lack microscopic realization theories.
• Existing theories have not rigorously derived a microscopic pathway for higher spin Kitaev models in solid-state materials.

Purpose of the Study:

• To theoretically derive a microscopic route for achieving spin S=1 Kitaev interactions in two-dimensional materials.
• To explore the potential of these systems for realizing quantum spin liquid states.
• To propose candidate materials and discuss generalizations for higher spin systems.

Main Methods:

• Theoretical derivation of spin S=1 Kitaev interaction in edge-shared octahedral systems.
• Analysis of superexchange and direct-exchange paths involving spin-orbit and Hund's coupling.
• Exact diagonalization technique to identify quantum spin liquid regimes.

Main Results:

• A theory for spin S=1 Kitaev interaction is presented, driven by strong spin-orbit coupling in anions and Hund's coupling in cations.
• Superexchange generates S=1 Kitaev and ferromagnetic Heisenberg interactions, while direct exchange yields antiferromagnetic Heisenberg interactions.
• The Kitaev interaction is shown to dominate the physics in the S=1 system.
• A finite regime of S=1 spin liquid is identified in the presence of Heisenberg interactions.

Conclusions:

• The study provides a viable microscopic route to higher spin Kitaev models in solid-state materials.
• Candidate materials are proposed, paving the way for experimental investigations of S=1 quantum spin liquids.
• The theoretical framework offers insights into generalizing Kitaev models to even higher spin values.