Ferrimagnetic Kitaev spin liquids in mixed spin 1/2 spin 3/2 honeycomb magnets

TL;DR

This paper investigates the realization of mixed-spin Kitaev models in honeycomb magnets, identifying conditions for quantum spin liquid phases through theoretical modeling and simulations, with implications for experimental materials.

Contribution

It develops a superexchange theory for mixed-spin systems and maps out the phase diagram, revealing four quantum spin liquid phases with potential experimental relevance.

Findings

Identification of four distinct quantum spin liquid phases.

Conditions for dominant Kitaev interactions in mixed-spin materials.

Role of spin-orbital couplings and quadrupolar orders in stabilizing phases.

Abstract

We explore the potential experimental realization of the mixed-spin Kitaev model in materials such as Zr$_{0.5}$Ru$_{0.5}$Cl$_3$, where spin-1/2 and spin-3/2 ions occupy distinct sublattices of a honeycomb lattice. By developing a superexchange theory specifically for this mixed-spin system, we identify the conditions under which dominant Kitaev-like interactions emerge. Focusing on the limiting case of pure Kitaev coupling with single-ion anisotropy, we employ a combination of superexchange theory, parton mean-field theory, and density matrix renormalization group (DMRG) simulations. We establish a comprehensive ground-state phase diagram identifying four distinct quantum spin liquid phases. Our findings highlight the importance of spin-orbital couplings and quadrupolar order parameters in stabilizing exotic phases, providing a foundation for exploring mixed-spin Kitaev magnets.