Competition between axial anomaly and ferromagnetic ordering in Bi2-xFexSe3-xSx topological insulator: A study of magnetic and magnetotransport properties

The topological insulators Bi2-xFexSe3-xSx have been investigated by the dc-magnetization, magnetotransport and angle resolved photoemission spectroscopy (ARPES) techniques. With doping of Fe and S, a negative giant magneto-resistance (MR) is observed for parallel electric and magnetic fields (H parallel to E). The MR behavior at lower magnetic field can be explained with the semi-classical theory whereas the MR behavior at higher field has been attributed to the axial anomaly. Interestingly, the system reached to the quantum limit at low magnetic field (similar to 4.5T). The magnetic ordering can be explained with the presence of both the RKKY (surface) and van-Vleck (bulk) interaction. The ARPES study reveals that a surface gap is suppressed when the magnetic ordering changes from ferromagnetic to anti-ferromagnetic ordering. The ARPES study and the appearance of quantum oscillations (SdH) in the resistivity pattern reveal that the topological surface property is preserved with the co-doping of Fe and S. (C) 2022 The Chinese Ceramic Society. Production and hosting by Elsevier B.V.

Automated summary

The topological insulators Bi2-xFexSe3-xSx were investigated using various techniques, revealing a negative giant magneto-resistance (MR) effect with parallel electric and magnetic fields under Fe and S doping. The magnetic ordering behavior was explained by both surface and bulk interactions. ARPES study and the presence of quantum oscillations supported the preservation of topological surface properties with co-doping of Fe and S.