Ultrahigh mobility and nonsaturating magnetoresistance in Heusler topological insulators

We report the transport properties of the proposed Heusler topological insulators YPtSb, LaPtBi, and LuPdSb. All compounds show ultrahigh hole mobility with value of 4124, 4275, and 1800 cm² V^-1 s^-1 for YPtBi, LaPtBi, and LuPdSb, respectively, at 300 K. The temperature dependence of mobility shows strong and weak phonon scattering for LaPtBi and LuPdSb, respectively, while YPtSb shows strong impurity scattering. These ultrahigh values of the mobility are not only due to gaplessness but also to the presence of linear dispersion of the bands close to the Fermi energy, where charge carriers behave like relativistic particles. Furthermore, nonsaturating magnetoresistance (MR) is observed in the temperature range 2--300 K that shows linear behavior at high fields. A tentative relationship between the linear MR and mobility is discussed, which indicates that the mobility controls the linear part of MR.