High-temperature transport investigation of the band structure in the half-Heusler RPtBi (R=rare earth) topological semimetals

The half-Heusler RPtBi (R=rare earth) compounds are predicted to be topological semimetals, driven by the strong spin-orbit coupling, which forms a quadratically touching p-orbital bands near the chemical potential. Quasiparticle excitations arising from the four-fold touching point are governed by the Luttinger-Kohn Hamiltonian, and their effective spin j=3/2 plays a crucial role in the magnetic interaction and the formation of Cooper pairs with up to total momentum J = 3 septet states. Although theoretical band structure has reached a consensus, it has not been experimentally verified. In particular, the angle-resolved photoemission spectroscopy and transport results have been inconsistent. High-temperature transport properties are dominated by thermally excited quasiparticles, which makes electrical resistance at temperatures above room temperature a promising probe for the band structure. In this work, we use a custom-built transport measurement apparatus in ultra-high vacuum to measure the electrical resistance in various RPtBi compounds and model the results to shed light on the predicted topological band structure.