Interplay between strong correlations and electronic topology in the underlying kagome lattice of Na2/3CoO2

TL;DR

This study investigates how strong electronic correlations and topology interact in Na2/3CoO2, revealing coexistence of light and heavy carriers, Dirac-like quasiparticles, and Lifshitz transitions, with implications for topological and correlated electron physics.

Contribution

It uncovers the interplay between correlations and topology in Na2/3CoO2, highlighting Dirac quasiparticles and Lifshitz transitions in a kagome lattice system.

Findings

Evidence for coexistence of light and heavy carriers.

Presence of Dirac-like quasiparticles suppressed by magnetic field.

Lifshitz transitions reveal lower mobility carriers and magnetic scattering effects.

Abstract

Electronic topology in metallic kagome compounds is under intense scrutiny. We present transport experiments in Na2/3CoO2 in which the Na order differentiates a Co kagome sub-lattice in the triangular CoO2 layers. Hall and magnetoresistance (MR) data under high fields give evidence for the coexistence of light and heavy carriers. At low temperatures, the dominant light carrier conductivity at zero field is suppressed by a B-linear MR suggesting Dirac like quasiparticles. Lifshitz transitions induced at large B and T unveil the lower mobility carriers. They display a negative B^2 MR due to scattering from magnetic moments likely pertaining to a flat band. We underline an analogy with heavy Fermion physics.