Evidence of magnetic fluctuation induced Weyl semimetal state in the antiferromagnetic topological insulator Mn(Bi1-xSbx)2Te4

Seng Huat Lee, David Graf, Robert Robinson, John Singleton, Johanna C. Palmstrom, Zhiqiang Mao

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We report c-axis transport studies on magnetic topological insulators Mn(Bi1-xSbx)2Te4. We performed systematic c-axis magnetoresistivity measurements under high magnetic fields (up to 35 T) on several representative samples. We find that the lightly hole- and lightly electron-doped samples, while both having the same order of magnitude of carrier density and similar spin-flop transitions, exhibit sharp contrast in electronic anisotropy and transport mechanism. The electronic anisotropy is remarkably enhanced for the lightly hole-doped sample relative to pristine MnBi2Te4 but not for the lightly electron-doped sample. The lightly electron-doped sample displays a giant negative longitudinal magnetoresistivity (LMR) induced by the spin-valve effect at the spin-flop transition field, whereas the lightly hole-doped sample exhibits remarkable negative LMR consistent with the chiral anomaly behavior of a Weyl semimetal. Furthermore, we find the large negative LMR of the lightly hole-doped sample extends to a wide temperature range above the Néel temperature (TN) where the magnetoconductivity is proportional to B2. This fact, together with the short-range intralayer ferromagnetic correlation revealed in isothermal magnetization measurements, suggests the possible presence of the Weyl state above TN. These results demonstrate that in the c-axis magnetotransport of Mn(Bi1-xSbx)2Te4, the spin scattering is dominant in the lightly electron-doped sample but overwhelmed by the chiral anomaly effect in the lightly hole-doped sample due to the presence of the Weyl state. These findings extend the understanding of the transport properties of Mn(Bi1-xSbx)2Te4.

Original languageEnglish (US)
Article number205105
JournalPhysical Review B
Issue number20
StatePublished - May 15 2023

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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