Growth and characterization of the magnetic topological insulator candidate Mn2Sb2Te5

Abstract

We report a new member of topological insulator (TI) family i.e. Mn2Sb2Te5, which belongs to MnSb2Te4 family and is a sister compound of Mn2Bi2Te5. An antiferromagnetic layer of (MnTe)2 has been inserted between quintuple layers of Sb2Te3. The crystal structure and chemical composition of as grown Mn2Sb2Te5 crystal is experimentally visualized by single crystal x-ray diffractometer and field emission scanning electron microscopy. The valence states of individual constituents i.e., Mn, Sb and Te are ascertained through x-ray photo electron spectroscopy. Different vibrational modes of Mn2Sb2Te5 are elucidated through Raman spectroscopy. Temperature-dependent resistivity ρ(T) of Mn2Sb2Te5 resulted in metallic behavior of the same with an up-turn at below around 20 K. Further, the magneto-transport ρ(T) vs H of the same exhibited negative magneto-resistance (MR) at low temperatures below 20 K and small positive at higher temperatures. The low Temperature −ve MR starts decreasing at higher fields. The magnetic moment as a function of temperature at 100 Oe and 1 kOe showed anti-ferromagnetism (AFM) like down turn cusps at around 20 K and 10 K. The isothermal magnetization showed AFM like loops with some embedded ferromagnetic/paramagnetic (PM) domains at 5 K and purely PM like at 100 K. The studied Mn2Sb2Te5 clearly exhibited the characteristics of a magnetic TI.