Crystal growth and magnetic evolution of antiferromagnetic topological insulator Zn-doped MnBi2Te4

Abstract

As the first intrinsic magnetic topological insulator, MnBi₂Te₄ has provided a material platform for the realization of various novel physical phenomena arising from the interaction between magnetism and band topology. Here, transition element Zn-doped MnBi₂Te₄ crystals of millimeter size, synthesized by using self-flux method, are reported. With increasing Zn content, the hexagonal lattice shrinks, and the Raman frequencies show a red shift. All samples undergo a transition from A-type antiferromagnetic (A-AFM) to canted antiferromagnetic (CAFM) to ferromagnetic (FM) under magnetic field. The antiferromagnetic ordering temperature slightly increases from 24.2 K for MnBi₂Te₄ to 25.2 K for Mn_0.75Zn_0.25Bi₂Te₄. The transition field from AFM to CAFM decreases from 3.4 T for x = 0–3.07 T for x = 0.25. Isothermal magnetization data suggest that the single-ion anisotropy of Mn²⁺ decrease and the interlayer magnetic interaction increase slightly due to the diluted magnetic ions and unit cell shrinkage. Samples Mn_0.9Zn_0.1Bi₂Te₄ and Mn_0.8Zn_0.2Bi₂Te₄ show metallic conduction with a cusplike anomaly at around T_N ≈ 24 K, corresponding to a long-range antiferromagnetic (AFM) transition. The increase of T_N and decrease of transition field ($H_c^{SF}$) upon Zn doping, make it possible to manipulate magnetic and electrical properties in topological insulators by non-magnetic element substitution, which is of great significance for further application in quantum information storage and spintronics.