Tuning the transport and magnetism in a Cr–Bi2Se3 topological insulator by Sb doping

Abstract

High-quality crystalline (Cr,Sb)-doped Bi₂Se₃ (Cr-BSS) films were synthesized using molecular beam epitaxy (MBE). The effect of Cr- and Sb-doping on the transport and magnetic properties of Cr-BSS films was systematically investigated. The sheet carrier density N_2D was found to be reduced to ∼6 × 10¹² cm⁻² in this quaternary compound at room temperature. This has not previously been observed in a Cr–Bi₂Se₃-based magnetic topological insulator (TI). Moreover, owing to the Sb dopants, the weak localization (WL)-like positive magnetoconductance in magnetic Cr–Bi₂Se₃ (Cr-BS) was enhanced. The enhancement is attributed to the emergence of ferromagnetism, as evidenced from the field-dependent Hall resistance and magnetic moment. The obvious tunable electrical and magnetic properties by the Sb dopant in this system are well suited for applications based on magnetic TI devices.