Antiferromagnetic topological insulating state in Tb0.02Bi1.08Sb0.9Te2S single crystals

Topological insulators are emerging materials with insulating bulk and symmetry protected nontrivial surface states. One of the most fascinating transport behaviors in a topological insulator is the quantized anomalous Hall insulator, which has been observed in magnetic-topological-insulator-based devices. In this work, we report a successful doping of rare earth element Tb into ${\mathrm{Bi}}_{1.08}{\mathrm{Sb}}_{0.9}{\mathrm{Te}}_{2}\mathrm{S}$ topological insulator single crystals, in which the Tb moments are antiferromagnetically ordered below $\ensuremath{\sim}10$ K. Benefiting from the in-bulk-gap Fermi level, transport behavior dominant by the topological surface states is observed below $\ensuremath{\sim}150$ K. At low temperatures, strong Shubnikov--de Haas oscillations are observed, which exhibit 2D-like behavior. The topological insulator with long range magnetic ordering in rare earth doped ${\mathrm{Bi}}_{1.08}{\mathrm{Sb}}_{0.9}{\mathrm{Te}}_{2}\mathrm{S}$ single crystal provides an ideal platform for quantum transport studies and potential applications.