Magnetic structure of Colossal Magnetoresistance Mn₃(Si_1-xGe_x)₂Te₆ under c-axis field

Recently discovered colossal magnetoresistance (CMR) Mn₃Si₂Te₆ [1–3] has shown stark contrast with conventional CMR manganites and pyrochlore materials. The resistivity in Mn₃Si₂Te₆ drops by orders of magnitude leading to an insulator-metal transition with an applied magnetic field just above 4 T. The CMR occurs only when the field is applied along the hard axis (c-axis), while such effect is absent with the field applied in the basal plane, where magnetization is fully saturated. Using single crystal neutron diffraction, we have conducted systematic study of the ground state spin structures of the parent and Ge-doped Mn₃Si₂Te₆ and evolution of the corresponding spin configurations with magnetic field up to 14 Tesla along the c-axis. The modification of the spin order and the relevant mechanism responsible for the CMR will be discussed [4].

[1] Y. Ni et al., Phys. Rev. B 103, L161105 (2021).

[2] J. Seo et al., Nature 599, 576 (2021).

[3] Y. Zhang et al., Nature (2022). https://doi.org/10.1038/s41586-022-05262-3

[4] F. Ye et al., to be published in Phys. Rev. B (2022).