Electronic, optical, and thermodynamic properties of a quantum spin liquid candidate NaRuO2: Ab-initio investigation

Abstract

Quantum spin liquids (QSLs), known for their competing interactions that prevent conventional ordering, exhibit emergent phenomena and exotic properties resulting from quantum correlations. Despite these recent advancements of QSLs, a significant portion of the optical and thermodynamic properties in the Kagome lattice remains unknown. In addition, the thermodynamic phenomenology of NaRuO2 bears resemblance that of highly frustrated magnets. Here, we employed ab-initio calculations to explore the electronic, optical and thermodynamic properties of NaRuO2, a new QSL candidate. NaRuO2 was identified as a semiconductor with a small bandgap energy of 0.69 eV. Our results reveal a huge anisotropic optical properties, in which distinct refractive index within the ab-plane indicating an impressive birefringent character of the NaRuO2 system, and a significant enhancement of the optical absorption coefficient and optical conductivity in the in-plane with respect the c-axis. The investigation also examines the electronic anisotropy of the gap energy, by applying strain the gap energy displays significant variations in the ab-plane compared to the out-of-plane direction. Conversely, calculations of the thermodynamic properties reveal a low thermal conductivity (2.5–0.5 W m−1. K−1) and specific heat, which suggests the existence of strong interactions among the NaRuO2 quantum spins. The calculated linear specific heat behavior in NaRuO2 suggests the fractionalization of electrons and the presence of a spinons Fermi surface. These findings hold promising potential for future quantum applications.