The noncentrosymmetric half Heusler compound YPtBi exhibits superconductivity below a critical temperature $T_c=0.77$ K with a zero-temperature upper critical field $H_{c2}\left(0\right)=1.5$ T. Magnetoresistance and Hall measurements support theoretical predictions that this material is a topologically nontrivial semimetal having a surprisingly low positive charge-carrier density of $2\times {10}^{18}$ cm${}^{-3}$. Unconventional linear magnetoresistance and beating in Shubnikov–de Haas oscillations point to spin-orbit split Fermi surfaces. The sensitivity of magnetoresistance to surface roughness suggests a possible contribution from surface states. The combination of noncentrosymmetry and strong spin-orbit coupling in YPtBi presents a promising platform for the investigation of topological superconductivity.

• Received 4 December 2011

DOI:https://doi.org/10.1103/PhysRevB.84.220504