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Crystal Growth and characterization of possible New Magnetic Topological Insulators FeBi2Te4

Here we report successful single crystal growth of new possible magnetic topological insulator (MTI) FeBi2Te4 by self-flux method via vacuum encapsulation process. The detailed Rietveld analysis of Powder XRD data shows the as grown MTI crystal to be mainly dominated by 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 144cm-1. The secondary split modes are result of FeTe intercalation in Bi2Te3 unit cell. Magneto-resistance measurement has been performed at different temperatures i.e. 200K, 20K and 2K in applied magnetic fields up to 12 Tesla, which showed very low MR in comparison to pure Bi2Te3 crystal. Temperature dependence of DC magnetization measurements show the FeBi2Te4 crystal to be mainly of ferromagnetic (FM) or ferri-magnetic nature above 295 K, albeit a secondary weak magnetic transition is seen at 54-46K as well. Detailed isothermal magnetization (MH) results showed that FM saturation moment at 295K is 0.00213emu/g, which is nearly invariant till 400 K. Summary, we had grown an MTI FeBi2Te4 single crystal, which may be a possible entrant for Quantum Anomalous Hall (QAH) effect at room temperature or above.