A $j_{\rm eff}=1/2$ Kitaev material on the triangular lattice: The case of NaRuO$_2

• Main Authors: Razpopov, Aleksandar, Kaib, David A. S, Backes, Steffen, Balents, Leon, Wilson, Stephen D, Ferrari, Francesco, Riedl, Kira, Valenti, Roser
• Format: Journal Article
• Language: English
• Published: 21-12-2022
• Subjects: Physics - Strongly Correlated Electrons
• DOI: 10.48550/arxiv.2212.11306

npj Quantum Mater. 8, 36 (2023) Motivated by recent reports of a quantum disordered ground state in the
triangular lattice compound NaRuO$_2$, we derive a $j_{\rm eff}=1/2$ magnetic
model for this system by means of first-principles calculations. The pseudospin
Hamiltonian is dominated by bond-dependent off-diagonal $\Gamma$ interactions,
complemented by a ferromagnetic Heisenberg exchange and a notably
antiferromagnetic Kitaev term. In addition to bilinear interactions, we find a
sizable four-spin ring exchange contribution with a strongly anisotropic
character, which has been so far overlooked when modeling Kitaev materials. The
analysis of the magnetic model, based on the minimization of the classical
energy and exact diagonalization of the quantum Hamiltonian, points toward the
existence of a rather robust easy-plane ferromagnetic order, which cannot be
easily destabilized by physically relevant perturbations.