Crystal Growth and Characterization of Possible New Magnetic Topological Insulators FeBi2Te4

Abstract

Here, we report successful single crystal growth of new possible magnetic topological insulator (MTI) FeBi2Te4 by a self-flux method via a vacuum encapsulation process. The detailed Rietveld analysis of powder XRD data shows the as-grown MTI crystal to be mainly dominated by the FeBi2Te4 phase along with minority phases of Bi2Te3 and FeTe. Scanning electron microscope (SEM) image shows the morphology of as-grown MTI single crystal to be of layered type laminar structure. Raman spectroscopy of the crystal exhibited three distinct phonon modes at 65, 110, and 132 cm−1 along with two split secondary modes at 90, and 144 cm−1. The secondary split modes are the result of FeTe intercalation in the Bi2Te3 unit cell. Magnetoresistance (MR%) measurement has been performed at different temperatures, i.e., 200 K, 20 K, and 2 K in applied magnetic fields up to ± 12 Tesla, which showed very low MR in comparison with pure Bi2Te3 crystal. Temperature dependence of DC magnetization measurements shows the FeBi2Te4 crystal to be mainly of ferromagnetic (FM) or ferrimagnetic nature above 295 K, albeit a secondary weak magnetic transition is seen at 54–46 K as well. Detailed isothermal magnetization (MH) results showed that the FM saturation moment at 295 K is 0.00213 emu/g, which is nearly invariant until 400 K. In summary, we had grown an MTI FeBi2Te4 single crystal, which may be a possible entrant for the quantum anomalous Hall (QAH) effect at room temperature or above.