Giant magnetoresistance across the magnetic-field induced semiconductor-semimetal transition in half-Heusler HoAuSn

The discovery of topological insulators and semimetals in zinc-blend HgTe and its relatives generates strong activity in building contemporary material science. Ternary half-Heusler compounds, which are not only related to the zinc-blends electronically but involve magnetic rare-earth ions, have served as an ideal platform to explore next-generation multifunctional topological states. However, most of them reported so far were band-inverted zero-gap semiconductors RPtBi and RPdBi.

Here, we report a new family of half-Heusler HoAuSn which is a trivial indirect semiconductor at zero magnetic field but revealed to show a large negative magnetoresistance exceeding four orders of magnitude at low temperatures. The combination of the Shubnikov-de Haas oscillation and first-principle band calculation suggests that the spin-gapless semiconductor, which host both the high mobility and high spin polarization, is realized via strong intra-atomic coupling between localized 4f magnetic moments and 5d itinerant electrons in Ho ions.

Our findings can open new research directions for the topological band engineering and magnetoelectric effects beyond binary compounds.