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 XRD (SCXRD) and field emission scanning electron microscopy (FESEM). The valence states of individual constituents i.e., Mn, Sb and Te are ascertained through X-ray photo electron spectroscopy (XPS). Different vibrational modes of Mn2Sb2Te5 are elucidated through Raman spectroscopy. Temperature-dependent resistivity (T) of Mn2Sb2Te5 resulted in metallic behaviour of the same with an up-turn at below around 20K. Further, the magneto-transport (T) vs H of the same exhibited negative magneto-resistance (MR) at low temperatures below 20K 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 100Oe and 1kOe showed AFM like down turn cusps at around 20K and 10K. The isothermal magnetization (MH) showed AFM like loops with some embedded FM/PM domains at 5K and purely paramagnetic (PM) like at 100K. The studied Mn2Sb2Te5 clearly exhibited the characteristics of a magnetic TI (MTI).