Electronic correlations and topology in Kondo insulator PuB$_6$

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 ($Δρ \sim$ 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.

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