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 order temperature slightly increases from 24.2 K for MnBi2Te4 to 25.2 K for Mn0.75Zn0.25Bi2Te4. The transition field from AFM to CAFM decreases from 3.4 T for x = 0 to 2.9 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 Mn0.9Zn0.1Bi2Te4 and Mn0.8Zn0.2Bi2Te4 show metallic conduction with a cusplike anomaly at around TN ≈ 24 K, corresponding to a long-range antiferromagnetic (AFM) transition. The increase of TN and decrease of transition field ([[EQUATION]]) 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.

Keywords: Magnetic topological insulator, Zn-doped MnBi2Te4, Single crystals； Antiferromagnetic ordering, Magnetic interaction；