Coupling between the spatially separated magnetism and the topological band revealed by magnetotransport measurements on EuMn1−xZnxSb2

We study the coupling between topological bands and two distinct magnetic sublattices in ${\mathrm{EuMn}}_{1\ensuremath{-}x}{\mathrm{Zn}}_{x}{\mathrm{Sb}}_{2}$ $(0\ensuremath{\le}x\ensuremath{\le}1)$ using a combination of magnetotransport measurements and density functional theory (DFT) calculations. Hall measurements reveal a low carrier concentration with high mobility across all samples, allowing the observation of quantum oscillation in the range of $0\ensuremath{\le}x\ensuremath{\le}0.8$ at a relatively low magnetic field. Upon analyzing the quantum oscillation data, the fast Fourier transform spectra for $0\ensuremath{\le}x\ensuremath{\le}0.8$ exhibit a relatively weak Zn doping dependency but a significant temperature dependency. This weak Zn doping dependency suggests that the magnetotransport properties of ${\mathrm{EuMn}}_{1\ensuremath{-}x}{\mathrm{Zn}}_{x}{\mathrm{Sb}}_{2}$ are dominated by quasi-two-dimensional small Fermi pockets originating from the Sb zigzag chains, which remain largely unaffected by varying Mn content. The significant temperature-dependent phase of the oscillation indicates that the topological state is tunable by the magnetism of Eu. Our observations suggest that the topological bands arising from Sb zigzag chains are sensitive to adjacent Eu magnetism but are relatively insensitive to more distant Mn atoms. Our experimental results are in good agreement with the DFT calculations, which show that Zn doping introduces only minor electron-type carriers at the Fermi level without substantially altering the Dirac bands. Our study will be helpful for understanding the mechanism of coupling between spatially separated magnetism and topological bands, offering insights that could be valuable for the design of materials with magnetism-tunable topological electronic structures.