Anisotropic Weak Antilocalization in Thin Films of the Weyl Semimetal TaAs

Device applications of topological semimetals await the development of epitaxial films in the ultrathin limit. Weak antilocalization (WAL) has been extensively utilized in the understanding of surface states in topological insulators and shows promise for use in elucidating the properties of thin film topological semimetals. Here, we report insights from WAL into surface state and interface transport properties of our recently synthesized, single-crystal-like thin films of Weyl semimetal TaAs(001) grown on GaAs(001). We observe robust, anisotropic WAL in the magnetoconductance from 2-20 K in films from 10 to 200 nm thick. We link the anisotropic WAL magnetoconductance to anisotropic mobility stemming from film topography. We conclude that WAL in the films likely originates from the antilocalization of topological surface states. The WAL magnetoconductance is impacted by the film thickness and topography, solidifying the useful role of WAL in the study of topological semimetal/semiconductor heterointerfaces.