Ferromagnetic (Sb2Te 3)1-x (MnSb2Te4)x Structures with High Curie Temperature Grown by Molecular Beam Epitaxy

Abstract Magnetic topological materials are promising for realizing novel quantum physical phenomena. Among these, bulk Mn-rich MnSb2Te4 is ferromagnetic due to MnSb antisites and has relatively high Curie temperatures (TC), which is attractive for technological applications. We have previously reported the growth of materials with the formula (Sb2Te3)1−x(MnSb2Te4)x. Here we report their magnetic and transport properties. We show that the samples are divided into three groups based on the percent septuple layers (SLs) within the crystals and their corresponding TC values. Samples that contain less than 70% or more than 90% SLs have a single TC value of 15-20K and 30-40K, respectively, while samples with between 70–80% SLs exhibit two TC values, one at ~ 30-40K and the second (TC2) reaching values above 80K, almost twice as high as any reported value to date for these type of materials. Structural analysis shows that samples with 70–80% SLs have large regions of only SLs, which should give rise to a TC of ~ 30-40K, while other regions have isolated QLs embedded within the SL lattice. We propose that the latter regions are responsible for the higher TC2 values. Our results have important implications for the design of magnetic topological materials having optimum properties.