Robust negative longitudinal magnetoresistance and spin–orbit torque in sputtered Pt3Sn and Pt3SnxFe1-x topological semimetal

Abstract

Contrary to topological insulators, topological semimetals possess a nontrivial chiral anomaly that leads to negative magnetoresistance and are hosts to both conductive bulk states and topological surface states with intriguing transport properties for spintronics. Here, we fabricate highly-ordered metallic Pt3Sn and Pt3SnxFe1-x thin films via sputtering technology. Systematic angular dependence (both in-plane and out-of-plane) study of magnetoresistance presents surprisingly robust quadratic and linear negative longitudinal magnetoresistance features for Pt3Sn and Pt3SnxFe1-x, respectively. We attribute the anomalous negative longitudinal magnetoresistance to the type-II Dirac semimetal phase (pristine Pt3Sn) and/or the formation of tunable Weyl semimetal phases through symmetry breaking processes, such as magnetic-atom doping, as confirmed by first-principles calculations. Furthermore, Pt3Sn and Pt3SnxFe1-x show the promising performance for facilitating the development of advanced spin-orbit torque devices. These results extend our understanding of chiral anomaly of topological semimetals and can pave the way for exploring novel topological materials for spintronic devices.

Structural Anisotropy-Driven Atomic Mechanisms of Phase Transformations in the Pt–Sn System

“…Atomic rearrangements captured by STEM imaging and spectroscopy showed a direct correlation between the type of anisotropy present in the crystal structure of either parent or product phase and the pathway involved in transforming to the product phase. Because the individual phases of the Pt–Sn system are still challenging to grow, especially in the form of thin films and nanoparticles , needed for applications in catalysis and spintronics, − successive solid to solid phase transformations discussed here serve as a promising alternative to direct synthesis. , …”