Electronic correlations and topology in Kondo insulator PuB$_6$

TL;DR

This paper combines experimental magneto-transport measurements and theoretical calculations to demonstrate that PuB$_6$ is a topological Kondo insulator with characteristic resistivity behavior and nontrivial topological properties.

Contribution

It provides experimental evidence and theoretical support for PuB$_6$ being a strongly correlated topological insulator with a low-temperature resistivity plateau and surface conduction.

Findings

Resistivity transition from thermally activated to plateau at low temperatures

Surface-to-volume resistivity dependence indicating surface conduction

GGA+U captures electronic and topological properties effectively

Abstract

Utilizing a combination of dynamical mean field theory and density functional theory (DMFT/DFT), it has been theoretically proposed that PuB$_6$ is a strongly correlated topological insulator characterized by nontrivial $\mathbf{Z}_{2}$ topological invariants and metallic surface states (\textit{X. Deng et al., Phys. Rev. Lett. 111, 176404 (2013)}). Here, we demonstrate through low-temperature magneto-transport measurements and first-principles calculations that PuB$6$ exhibits characteristics of a topological Kondo insulating state. These features include a transition in electrical resistivity from high-temperature, thermally activated behavior with a narrow gap at the Fermi level ($\Delta{\rho} \sim$ 20 meV) to a distinctive low-temperature plateau, as well as a surface-to-volume dependence of electrical resistivity at low temperatures. The topological nature of PuB$_6$ is further supported by the theoretical calculations, which show that GGA+$U$ is capable of capturing electronic, topological, and lattice properties of PuB$_6$ with much lower computational cost than DMFT.