Browsing by Author "Li, SS"

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    Giant linear magnetoresistance in half-metallic Sr2CrMoO6 thin films
    (Springer Nature, 2021-12-01) Wang, ZC; Chen, L; Li, SS; Ying, JS; Tang, F; Gao, GY; Fang, Y; Zhao, WY; Cortie, DL; Wang, XL; Zheng, RK
    Linear magnetoresistance (LMR) is a special case of a magnetic-field induced resistivity response, which has been reported in highly disordered semiconductor systems and in topological materials. In this work, we observe LMR effect in half-metallic perovskite Sr2CrMoO6 thin films, of which the maximum MR value exceeds +1600% at 2 K and 14 T. It is an unusual behavior in ferrimagnetic double perovskite material like Sr2CrMoO6, which are known for intrinsic tunneling-type negative magnetoresistance. In the thin films, the high carriers’ density (~1022 cm−3) and ultrahigh mobility (~104 cm2 V−1 s−1) provide a low-resistivity (~10 nΩ·cm) platform for spin-polarized current. Our DFT calculations and magnetic measurements further support the half-metal band structure. The LMR effect in Sr2CrMoO6 could possibly originate from transport behavior that is governed by the guiding center motion of cyclotron orbitals, where the magnetic domain structure possibly provides disordered potential. The ultrahigh mobility and LMR in this system could broaden the applications of perovskites, and introduce more research on metallic oxide ferri-/ferro-magnetic materials. © The Author(s) 2021 - Open Access CC BY licence.
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    Magnetotransport and Berry phase tuning in Gd-doped Bi2Se3 topological insulator single crystals
    (American Physical Society, 2022-05-01) Chen, L; Li, SS; Zhao, W; Bake, A; Cortie, DL; Wang, XL; Karel, J; Li, H; Zheng, RK
    The Berry phase is an important concept in solids, correlated to the band topology, axion electrodynamics, and potential applications of topological materials. Here, we investigate the magnetotransport and Berry phase of rare earth element Gd-doped Bi2Se3 (Gd:Bi2Se3) topological insulators (TIs) at low temperatures and high magnetic fields. Gd:Bi2Se3 single crystals show Shubnikov-de Haas (SdH) oscillations with nontrivial Berry phase, while Bi2Se3 single crystals show zero Berry phase in SdH oscillations. A fitting of the temperature-dependent magnetization curves using the Curie-Weiss law reveals that the Gd dopants in the crystals show paramagnetism in the 3-300 K region, indicating that the origin of the Berry phase is not long-range magnetic ordering. Moreover, Gd doping has limited influence on the quantum oscillation parameters (e.g., frequency of oscillation, area of Fermi surface, effective electron mass, and Fermi wave vectors) but has a significant impact on the Hall mobility, carrier density, and band topology. Our results demonstrate that Gd doping can tune the Berry phase of TIs effectively, which may pave the way for the future realization of many predicted exotic transport phenomena of topological origin. ©2022 American Physical Society